Engineering accomplishment-Air traffic control systems Essay

Engineering accomplishment-Air traffic control systems - Essay Example moved during the day with sufficient lighting and a clear sky. This meant that a pilot could easily see other aircrafts when taking off, landing or when on flight on the sky. Traffic avoidance was based on ‘see and be seen’ principle. This implied that aircrafts could only be flown in conditions that would easily allow them to see other aircrafts and change their flight paths to avoid others. All pilots were expected to abide by this principle and were also not allowed to fly the aircrafts under cloudy conditions. Furthermore, pilots were only allowed to fly the aircrafts in areas where visibility was not less than 3 miles. Nolan (2010) notes that pilots and aviation operators were comfortable with these rules since the aircrafts of those days were slow and pilots could easily see and avoid other aircrafts on flight making the establishment of more organized system of aircraft control unnecessary. Nevertheless, as technology advanced and people began to move all over the world in 1930s, their came a need of a more advanced air traffic control system to allow aircrafts to be flown at anytime, day or night, irrespective of prevailing condition leading to the establishment of instruments that would allow pilots to navigate the aircraft without having to depend on visual inference to the natural horizon. In addition, Navigation aids (navaids), which are ground-based systems, were also constructed to allow pilots to be able to control aircrafts without reference to ground (Gorton, 1998). When all these systems had been put in place, pilots could now be able to have easy take-off, travel en route and safely land in poor whether conditions that cannot allow them to see and avoid other aircrafts. This invention is indeed, a great accomplishment in the field of the aviation industry, which has helped improve aircraft movement throughout the country irrespective of whether condition, day or night. The reason being, it helps pilots in controlling the aircraft s thereby avoiding collision and accidents. For instance, it is reported that during peak hours in the US, approximately 5,000 aircrafts are flown on the sky every hour (Federal Aviation Administration, 2008). Mathematically, this figure translates to 50,000 airplanes being flown on the sky on a daily basis. This implies that without proper control mechanism, there could be high chances of these airplanes colliding with each other. It is here that air traffic control system comes in to ensure safe operation of aircrafts. For instance, a visit at most of the airports in Canada and the US, one thing for sure that one will see is an air traffic controller. The duty of an air traffic controller basically is to regulate aircraft take-offs and landings as required (Nolan, 2010). This is arguably the earliest method which involves the controller standing at a strategic position with colored flags which he or she uses to communicate with the pilots. For example, raising a green flag means t hat the pilot is at liberty to proceed with their planned landing or takeoffs. On the other hand, waving of a red flag implies that the pilot should hold on until controllers are sure that the pilots are free to proceed, when the green flag is waved according to Gorton (1998). This has indeed help reduce instances of aircraft accidents and collisions during landing and takeoff thereby restoring traveler’s confidence on the safety of aircrafts. However, since the safety of the aircraft is still has to be maintained on the sky this lead to the

Research, identify and discuss the 4 basic functions of management Essay

Research, identify and discuss the 4 basic functions of management. .Week TWO - Essay Example Having done a SWOT analysis, it can then proceed to making a more detailed strategic plan. An example of the planning stage is when a marketing manager designs a marketing plan in launching a new product. Wijesinghe enumerates various positive characteristics of planning such as being â€Å"goal-oriented, primacy, pervasive, flexible, continuous, involves choice, futuristic and involves mental exercise† (Wijesinghe, 2010, par 5). The second function of management is organizing. Organizing involves gathering all the resources of the company including the physical, human and financial resources. The tasks or activities that are needed to be done should be classified and assigned to the particular departments and individuals. Responsibilities are created and authorities delegated (Norman, n.d.). The organizing function of management is important because it encourages specialization, describes the work that must be done and by whom and it categorizes authority and command (Wijesinghe, 2010). Leading is the third management function. Under this function, the manager motivates and positively influences the employees so that they will be able to perform their tasks well. Managers should learn to communicate effectively with the employees to ensure that the company’s goals are achieved. Providing for monetary as well as non-monetary incentives may be necessary to influence and motivate the employees. Managers must be able to teach and assist the employees especially when they are faced with difficulties in performing their duties. The last function of management is controlling. Controlling involves â€Å"measuring achievement against established objectives and goals† (Norman, n.d., par 5). If there is any deviation from the achievement of the goals, the manager must identify the reason for the deviation and think of a way to correct it (Norman, n.d.). Monitoring and evaluating employee performance is a part

Computer Network Security within Organisations

Computer Network Security within Organisations Networking and Management Introduction A computer network is a connection of two or more computers in order to share resources and data. These shared resources can include devices like printers and other resources like electronic mail, internet access, and file sharing. A computer network can also be seen as a collection of Personal computers and other related devices which are connected together, either with cables or wirelessly, so that they can share information and communicate with one another. Computer networks vary in size. Some networks are needed for areas within a single office, while others are vast or even span the globe. Network management has grown as a career that requires specialized training, and comes with management of important responsibilities, thus creating future opportunities for employment. The resulting expected increase in opportunities should be a determining and persuasive factor for graduates to consider going into network management. Computer networking is a discipline of engineering that involves communication between various computer devices and systems. In computer networking, protocols, routers, routing, and networking across the public internet have specifications that are defined in RFC documents. Computer networking can be seen as a sub-category of computer science, telecommunications, IT and/or computer engineering. Computer networks also depend largely upon the practical and theoretical applications of these engineering and scientific disciplines. In the vastly technological environment of today, most organisations have some kind of network that is used every day. It is essential that the day-to-day operations in such a company or organisation are carried out on a network that runs smoothly. Most companies employ a network administrator or manager to oversee this very important aspect of the company’s business. This is a significant position, as it comes with great responsibilities because an organisation will experience significant operational losses if problems arise within its network. Computer networking also involves the setting up of any set of computers or computer devices and enabling them to exchange information and data. Some examples of computer networks include: Local area networks (LANs) that are made up of small networks which are constrained to a relatively small geographic area. Wide area networks (WANs) which are usually bigger than local area networks, and cover a large geographic area. Wireless LANs and WANs (WLAN WWAN). These represent the wireless equivalent of the Local Area Network and Wide Area Networks Networks involve interconnection to allow communication with a variety of different kinds of media, including twisted-pair copper wire cable, coaxial cable, optical fiber, and various wireless technologies. The devices can be separated by a few meters (e.g. via Bluetooth) or nearly unlimited distances (e.g. via the interconnections of the Internet. (http://en.wikipedia.org/wiki/Computer_networking) TASK 1 TCP connection congestion control Every application, whether it is a small or large application, should perform adaptive congestion control because applications that perform congestion control use a network more efficiently and are generally of better performance. Congestion control algorithms prevent the network from entering Congestive Collapse. Congestive Collapse is a situation where, although the network links are being heavily utilized, very little useful work is being done. The network will soon begin to require applications to perform congestion control, and those applications which do not perform congestion control will be harshly penalized by the network, probably in the form of preferentially dropping their packets during times of congestion (http://www.psc.edu/networking/projects/tcpfriendly/) Principles of Congestion Control Informally, congestion entails that too many sources are sending too much data, and sending them too fast for the network to handle. TCP Congestion Control is not the same as flow control, as there are several differences between TCP Congestion Control and flow control. Other principles of congestion control include Global versus point-2-point, and orthogonal issues. Congestion manifests itself by causing loss of packets (buffer overflow at routers), and long delays (queuing in router buffers). Also, during congestion, there is no explicit feedback from network routers, and there is congestion inferred from end-system observed loss. In network-assisted congestion control, routers provide feedback to end systems, and the explicit rate sender sends at –Choke Packet. Below are some other characteristics and principles of congestion control: When CongWin is below Threshold, sender in slow-start phase, window grows exponentially. When CongWin is above Threshold, sender is in congestion-avoidance phase, window grows linearly. When a triple duplicate ACK occurs, Threshold set to CongWin/2 and CongWin set to Threshold. When timeout occurs, Threshold set to CongWin/2 and CongWin is set to 1 MSS. Avoidance of Congestion It is necessary for the TCP sender to use congestion avoidance and slow start algorithms in controlling the amount of outstanding data that is injected into a network. In order to implement these algorithms, two variables are added to the TCP per-connection state. The congestion window (cwnd) is a sender-side limit on the amount of data the sender can transmit into the network before receiving an acknowledgment (ACK), while the receivers advertised window (rwnd) is a receiver-side limit on the amount of outstanding data. The minimum of cwnd and rwnd governs data transmission. (Stevens, W. and Allman, M. 1998) TCP Flow Control In TCP flow control, the receiving side of the TCP connection possesses a receive buffer, and a speed-matching service which matches the send rate to the receiving application’s drain rate. During flow control, Rcvr advertises any spare room by including value of RcvWindow in segments, and the sender limits unACKed data to RcvWindow. TCP flow control also ensures that there is no overflow of the receive buffer. Round-trip Time Estimation and Timeout TCP Round Trip Time and Timeout are usually longer than RTT, but RTT varies, and has a slow reaction to segment loss. SampleRTT is measured time from segment transmission until ACK receipt, ignore retransmissions, and will vary, want estimated RTT â€Å"smoother† Round-trip time samples arrive with new ACKs. The RTT sample is computed as the difference between the current time and a time echo field in the ACK packet. When the first sample is taken, its value is used as the initial value for srtt. Half the first sample is used as the initial value for rttvar. (Round-Trip Time Estimation and RTO Timeout Selection) There are often problems due to timeouts, including the restriction of the sender that is compelled to wait until a timeout, and is able to do nothing during this period. Also, the first segment in the sliding window is often not acked, and retransmission becomes necessary, waiting again one RTT before the segment flow continues. It should be noted that on receiving the later segments, the receiver sends back ACKs. Estimated RTT EstimatedRTT = 0.875 * EstimatedRTT + 0.125 * SampleRTT DevRTT DevRTT = (1 0.25) * DevRTT + | SampleRTT – EstimatedRTT Timeout interval TimeoutInterval = EstimatedRTT + 4 * DevRTT The integrated services (IntServ) and DiffServ (Differentiated Services) architecture are two architectures that have been proposed for the provision of and guaranteeing of quality of service (QoS) over the internet. Whereas the Intserv framework is developed within the IETF to provide individualized QoS guarantees to individual application sessions, Diffserv is geared towards enabling the handling of different classes of traffic in various ways on the internet. These two architectures represent the IETF’s current standards for provision of QoS guarantees, although neither Intserv nor Diffserv have taken off or found widespread acceptance on the web. (a) Integrated Service Architecture In computer networking, the integrated services (IntServ) architecture is an architecture that specifies the elements for the guaranteeing of quality of service (QoS) on the network. For instance, IntServ can be used to allow sound and video to be sent over a network to the receiver without getting interrupted. IntServ specifies a fine-grained Quality of service system, in contrast to DiffServs coarse-grained system of control. In the IntServ architecture, the idea is that each router inside a system implements IntServ, and applications which require various types of guarantees have to make individual reservations. Flow Specs are used to describe the purpose of the reservation, and the underlying mechanism that signals it across the network is called RSVP. TSPECs include token bucket algorithm parameters. The idea is that there is a token bucket which slowly fills up with tokens, arriving at a constant rate. Every packet which is sent requires a token, and if there are no tokens, then it cannot be sent. Thus, the rate at which tokens arrive dictates the average rate of traffic flow, while the depth of the bucket dictates how large the traffic is allowed to be. TSPECs typically just specify the token rate and the bucket depth. For example, a video with a refresh rate of 75 frames per second, with each frame taking 10 packets, might specify a token rate of 750Hz, and a bucket depth of only 10. The bucket depth would be sufficient to accommodate the burst associated with sending an entire frame all at once. On the other hand, a conversation would need a lower token rate, but a much higher bucket depth. This is because there are often pauses in conversations, so they can make do with fewer tokens by not sending the gaps between words and sentences. However, this means the bucket depth needs to be increased to compensate for the traffic being larger. (http://en.wikipedia.org/wiki/Integrated_services) (b) Differentiated Service Architecture The RFC 2475 (An Architecture for Differentiated Services) was published In 1998, by the IETF. Presently, DiffServ has widely replaced other Layer 3 Quality of Service mechanisms (such as IntServ), as the basic protocol that routers use to provide different service levels. DiffServ (Differentiated Services) architecture is a computer networking architecture which specifies a scalable, less complex, coarse-grained mechanism for the classification, management of network traffic and for provision of QoS (Quality of Service) guarantees on modern IP networks. For instance, DiffServ can be used for providing low-latency, guaranteed service (GS) to video, voice or other critical network traffic, while ensuring simple best-effort traffic guarantees to non-critical network services like file transfers and web traffic. Most of the proposed Quality of Service mechanisms which allowed these services to co-exist were complicated and did not adequately meet the demands Internet users because modern data networks carry various kinds of services like streaming music, video, voice, email and also web pages. It would probably be difficult to implement Intserv in the core of the internet because most of the communication between computers connected to the Internet is based on a client/server structural design. This Client/server describes a structure involving the connection of one computer to another for the purpose of giving work instructions or asking it questions. In an arrangement like this, the particular computer that questions and gives out instructions is the client, while the computer that provides answers to the asked questions and responds to the work instructions is the server. The same terms are used to describe the software programs that facilitate the asking and answering. A client application, for instance, presents an on-screen interface for the user to work with at the client computer; the server application welcomes the client and knows how to respond correctly to the clients commands. Any file server or PC can be adapted for use as an Internet server, however a dedicated computer should be chosen. Anyone with a computer and modem can join this network by using a standard phone. Dedicating the server that is, using a computer as a server only helps avoid some security and basic problems that result from sharing the functions of the server. To gain access to the Internet you will require an engineer to install the broadband modem. Then you will be able to use the server to network the Internet on all machines on a network. (www.redbooks.ibm.com/redbooks/pdfs/sg246380.pdf) TASK 5 Network security These days, computers are used for everything from shopping and communication to banking and investment. Intruders into a network system (or hackers) do not care about the privacy or identity of network users. Their aim is to gain control of computers on the network so that they can use these systems to launch attacks on other computer systems. Therefore people who use the network for these purposes must be protected from unknown strangers who try to read their sensitive documents, or use their computer to attack other systems, and send forged email, or access their personal information (such as their bank or other financial statements) Security Clauses The International Organisation for Standardizations (ISOs) 17799: 2005 Standard is a code of practice for information security management which provides a broad, non-technical framework for establishing efficient IT controls. The ISO 17799 Standard consists of 11 clauses that are divided into one or more security categories for a total of 39 security categories The security clauses of the ISO standard 17799:2005- code of practice for Information Security Management include: The security Policy clause Organizing Information Security Asset Management. Human Resources Security. Physical and Environmental Security. Communications and Operations. Access Control. Information Systems Acquisition, Development, and Maintenance. Information Security Incident Management. Business Continuity Management. Compliance. (http://www.theiia.org/ITAuditArchive/index.cfm?act=ITAudit.printiiid=467aid=2209) Here is a brief description of the more recent version of these security clauses: Security Policy: Security policies are the foundation of the security framework and provide direction and information on the companys security posture. This clause states that support for information security should be done in accordance with the companys security policy. Organizing Information Security: This clause addresses the establishment and organizational structure of the security program, including the appropriate management framework for security policy, how information assets should be secured from third parties, and how information security is maintained when processing is outsourced. Asset Management: This clause describes best practices for classifying and protecting assets, including data, software, hardware, and utilities. The clause also provides information on how to classify data, how data should be handled, and how to protect data assets adequately. Human Resources Security: This clause describes best practices for personnel management, including hiring practices, termination procedures, employee training on security controls, dissemination of security policies, and use of incident response procedures. Physical and Environmental Security: As the name implies, this clause addresses the different physical and environmental aspects of security, including best practices organizations can use to mitigate service interruptions, prevent unauthorized physical access, or minimize theft of corporate resources. Communications and Operations: This clause discusses the requirements pertaining to the management and operation of systems and electronic information. Examples of controls to audit in this area include system planning, network management, and e-mail and e-commerce security. Access Control: This security clause describes how access to corporate assets should be managed, including access to digital and nondigital information, as well as network resources. Information Systems Acquisitions, Development, and Maintenance: This section discusses the development of IT systems, including applications created by third-parties, and how security should be incorporated during the development phase. Information Security Incident Management: This clause identifies best practices for communicating information security issues and weaknesses, such as reporting and escalation procedures. Once established, auditors can review existing controls to determine if the company has adequate procedures in place to handle security incidents. Business Continuity Management: The 10th security clause provides information on disaster recovery and business continuity planning. Actions auditors should review include how plans are developed, maintained, tested, and validated, and whether or not the plans address critical business operation components. Compliance: The final clause provides valuable information auditors can use when identifying the compliance level of systems and controls with internal security policies, industry-specific regulations, and government legislation. (Edmead, M. T. 2006 retrieved from http://www.theiia.org/ITAuditArchive/?aid=2209iid=467) The standard, which was updated in June 2005 to reflect changes in the field of information security, provides a high-level view of information security from different angles and a comprehensive set of information security best practices. More specifically, ISO 17799 is designed for companies that wish to develop effective information security management practices and enhance their IT security efforts. Control Objectives The ISO 17799 Standard contains 11 clauses which are split into security categories, with each category having a clear control objective. There are a total of 39 security categories in the standard. The control objectives in the clauses are designed to meet the risk assessment requirements and they can serve as a practical guideline or common basis for development of effective security management practices and organisational security standards. Therefore, if a company is compliant with the ISO/IEC 17799 Standard, it will most likely meet IT management requirements found in other laws and regulations. However, because different standards strive for different overall objectives, auditors should point out that compliance with 17799 alone will not meet all of the requirements needed for compliance with other laws and regulations. Establishing an ISO/IEC 17799 compliance program could enhance a companys information security controls and IT environment greatly. Conducting an audit evaluation of the standard provides organizations with a quick snapshot of the security infrastructure. Based on this snapshot, senior managers can obtain a high-level view of how well information security is being implemented across the IT environment. In fact, the evaluation can highlight gaps present in security controls and identify areas for improvement. In addition, organizations looking to enhance their IT and security controls could keep in mind other ISO standards, especially current and future standards from the 27000 series, which the ISO has set aside for guidance on security best practices. (Edmead, M. T. 2006 retrieved from http://www.theiia.org/ITAuditArchive/?aid=2209iid=467) Tree Topology Tree topologies bind multiple star topologies together onto a bus. In its most simple form, only hub devices are directly connected to the tree bus and the hubs function as the root of the device tree. This bus/star hybrid approach supports future expandability of the network much better than a bus (limited in the number of devices due to the broadcast traffic it generates) or a star (limited by the number of hub ports) alone. Topologies remain an important part of network design theory. It is very simple to build a home or small business network without understanding the difference between a bus design and a star design, but understanding the concepts behind these gives you a deeper understanding of important elements like hubs, broadcasts, ports, and routes. (www.redbooks.ibm.com/redbooks/pdfs/sg246380.pdf) Use of the ring topology should be considered for use in medium sized companies, and the ring topology would also be the best topology for small companies because it is ensures ease of data transfer. Ring Topology In a ring network, there are two neighbors for each device, so as to enable communication. Messages are passed in the same direction, through a ring which is effectively either counterclockwise or clockwise. If any cable or device fails, this will break the loop and could disable the entire network. Bus Topology Bus networks utilize a common backbone to connect various devices. This backbone, which is a single cable, functions as a shared medium of communication which the devices tap into or attach to, with an interface connector. A device wanting to communicate with another device on the network sends a broadcast message onto the wire that all other devices see, but only the intended recipient actually accepts and processes the message. (www.redbooks.ibm.com/redbooks/pdfs/sg246380.pdf) Star Topology The star topology is used in a lot of home networks. A star network consists of a central connection point or hub that can be in the form of an actual hub, or a switch. Usually, devices will connect to the switch or hub by an Unshielded Twisted Pair (UTP) Ethernet. Compared to the bus topology, a star network generally requires more cable, but a failure in any star network cable will only take down one computers network access and not the entire LAN. If the hub fails, however, the entire network also fails. (www.redbooks.ibm.com/redbooks/pdfs/sg246380.pdf) Relating the security clauses and control objectives to an organisation In an organisation like the Nurht’s Institute of Information Technology (NIIT), the above mentioned security clauses and control objectives provide a high-level view of information security from different angles and a comprehensive set of information best security practices. Also, the ISO 17799 is designed for companies like NIIT, which aim to enhance their IT security, and to develop effective information security management practices. At NIIT, the local network relies to a considerable degree, on the correct implementation of these security practices and other algorithms so as to avoid congestion collapse, and preserve network stability. An attacker or hacker on the network can cause TCP endpoints to react in a more aggressive way in the face of congestion, by the forging of excessive data acknowledgments, or excess duplicate acknowledgments. Such an attack could possibly cause a portion of the network to go into congestion collapse. The Security Policy clause states that â€Å"support for information security should be done in accordance with the companys security policy.† (Edmead, M. T. 2006). This provides a foundation of the security framework at NIIT, and also provides information and direction on the organisation’s security posture. For instance, this clause helps the company auditors to determine whether the security policy of the company is properly maintained, and also if indeed it is to be disseminated to every employee. The Organizing Information Security clause stipulates that there should be appropriate management framework for the organisation’s security policy. This takes care of the organizational structure of NIIT’s security program, including the right security policy management framework, the securing of information assets from third parties, and the maintenance of information security during outsourced processing. At NIIT, the Security clauses and control objectives define the company’s stand on security and also help to identify the vital areas considered when implementing IT controls. The ISO/IEC 17799s 11 security clauses enable NIIT to accomplish its security objectives by providing a comprehensive set of information security best practices for the company to utilize for enhancement of its IT infrastructure. Conclusion Different businesses require different computer networks, because the type of network utilized in an organisation must be suitable for the organisation. It is advisable for smaller businesses to use the LAN type of network because it is more reliable. The WAN and MAN would be ideal for larger companies, but if an organisation decides to expand, they can then change the type of network they have in use. If an organisation decides to go international, then a Wireless Area Network can be very useful Also, small companies should endeavor to set up their network by using a client/server approach. This would help the company to be more secure and enable them to keep in touch with the activities of others are doing. The client/server would be much better than a peer-to-peer network, it would be more cost-effective. On the average, most organisations have to spend a good amount of money and resources to procure and maintain a reliable and successful network that will be and easy to maintain in the long run. For TCP Congestion Control, when CongWin is below Threshold, sender in slow-start phase, window grows exponentially. If CongWin is above Threshold, sender is in congestion-avoidance phase, window grows linearly. When a triple duplicate ACK occurs, Threshold set to CongWin/2 and CongWin set to Threshold, and threshold set to CongWin/2 and CongWin is set to 1 MSS when a timeout occurs. For a Small Office/Home Office (SOHO), networks such as wireless networks are very suitable. In such a network, there won’t be any need to run wires through walls and under carpets for connectivity. The SOHO user need not worry about plugging their laptop into docking stations every time they come into the office or fumble for clumsy and unattractive network cabling. Wireless networking provides connectivity without the hassle and cost of wiring and expensive docking stations. Also, as the business or home office grows or shrinks, the need for wiring new computers to the network is nonexistent. If the business moves, the network is ready for use as soon as the computers are moved. For the wired impossible networks such as those that might be found in warehouses, wireless will always be the only attractive alternative. As wireless speeds increase, these users have only brighter days in their future. (http://www.nextstep.ir/network.shtml) It is essential to note that the computer network installed in an organisation represents more than just a simple change in the method by which employees communicate. The impact of a particular computer network may dramatically affect the way employees in an organisation work and also affect the way they think. Bibliography Business Editors High-Tech Writers. (2003, July 22). International VoIP Council Launches Fax-Over-IP Working Group. Business Wire. Retrieved July 28, 2003 from ProQuest database. Career Directions (2001 October). Tech Directions, 61(3), 28 Retrieved July 21, 2003 from EBSCOhost database Edmead, M. T. (2006) Are You Familiar with the Most Recent ISO/IEC 17799 Changes? (Retrieved from http://www.theiia.org/ITAuditArchive/?aid=2209iid=467) FitzGerald, J. (1999), Business Data Communications And Networking Pub: John Wiley Sons Forouzan, B. (1998), Introduction To Data Communications And Networking Pub: Mc- Graw Hill http://www.theiia.org/itaudit http://www.theiia.org/ITAuditArchive/index.cfm?act=ITAudit.printiiid=467aid=2209 http://www.psc.edu/networking/projects/tcpfriendly/ ISO/IEC 17799:2000 – Code of practice for information security management Published by ISO and the British Standards Institute [http://www.iso.org/] ISO/IEC 17799:2005, Information technology – Security techniques – Code of practice for information security management. Published by ISO [http://www.iso.org/iso/en/prods-services/popstds/informationsecurity.html] Kurose, J. F. Ross, K. W. 2002. Computer Networking A Top-Down Approach Featuring the Internet, 2nd Edition, ISBN: 0-321-17644-8 (the international edition), ISBN: 0-201-97699-4, published by Addison-Wesley, 2002 www.awl.com/cs Ming, D. R. Sudama (1992) NETWORK MONITORING EXPLAINED: DESIGN AND APPLICATION Pub: Ellis Horwood Rigney, S. (1995) NETWORK PLANNING AND MANAGMENT YOUR PERSONAL CONSALTANT Round-Trip Time Estimation and RTO Timeout Selection (retrieved from http://netlab.cse.yzu.edu.tw/ns2/html/doc/node368.html) Shafer, M. (2001, June 11). Careers not so secure? Network Computing, 12(12), 130- Retrieved July 22, 2003 from EBSCOhost database Stevens, W. and Allman, M. (1998) TCP Implementation Working Group (retrieved from http://www.ietf.org/proceedings/98aug/I-D/draft-ietf-tcpimpl-cong-control-00.txt) Watson, S (2002). The Network Troubleshooters. Computerworld 36(38), 54. (Retrieved July 21, 2003 from EBSCOhost database) Wesley, A. (2000), Internet Users Guide to Network Resource Tools 1st Ed, Pub: Netskils www.microsoft.co.uk www.apple.com www.apple.co.uk www.bized.com http://www.nextstep.ir/network.shtml www.novell.com www.apple.com/business www.microsoft.com/networking/e-mails www.engin.umich.edu www.microsoft.com Computer Network Security within Organisations Computer Network Security within Organisations Networking and Management Introduction A computer network is a connection of two or more computers in order to share resources and data. These shared resources can include devices like printers and other resources like electronic mail, internet access, and file sharing. A computer network can also be seen as a collection of Personal computers and other related devices which are connected together, either with cables or wirelessly, so that they can share information and communicate with one another. Computer networks vary in size. Some networks are needed for areas within a single office, while others are vast or even span the globe. Network management has grown as a career that requires specialized training, and comes with management of important responsibilities, thus creating future opportunities for employment. The resulting expected increase in opportunities should be a determining and persuasive factor for graduates to consider going into network management. Computer networking is a discipline of engineering that involves communication between various computer devices and systems. In computer networking, protocols, routers, routing, and networking across the public internet have specifications that are defined in RFC documents. Computer networking can be seen as a sub-category of computer science, telecommunications, IT and/or computer engineering. Computer networks also depend largely upon the practical and theoretical applications of these engineering and scientific disciplines. In the vastly technological environment of today, most organisations have some kind of network that is used every day. It is essential that the day-to-day operations in such a company or organisation are carried out on a network that runs smoothly. Most companies employ a network administrator or manager to oversee this very important aspect of the company’s business. This is a significant position, as it comes with great responsibilities because an organisation will experience significant operational losses if problems arise within its network. Computer networking also involves the setting up of any set of computers or computer devices and enabling them to exchange information and data. Some examples of computer networks include: Local area networks (LANs) that are made up of small networks which are constrained to a relatively small geographic area. Wide area networks (WANs) which are usually bigger than local area networks, and cover a large geographic area. Wireless LANs and WANs (WLAN WWAN). These represent the wireless equivalent of the Local Area Network and Wide Area Networks Networks involve interconnection to allow communication with a variety of different kinds of media, including twisted-pair copper wire cable, coaxial cable, optical fiber, and various wireless technologies. The devices can be separated by a few meters (e.g. via Bluetooth) or nearly unlimited distances (e.g. via the interconnections of the Internet. (http://en.wikipedia.org/wiki/Computer_networking) TASK 1 TCP connection congestion control Every application, whether it is a small or large application, should perform adaptive congestion control because applications that perform congestion control use a network more efficiently and are generally of better performance. Congestion control algorithms prevent the network from entering Congestive Collapse. Congestive Collapse is a situation where, although the network links are being heavily utilized, very little useful work is being done. The network will soon begin to require applications to perform congestion control, and those applications which do not perform congestion control will be harshly penalized by the network, probably in the form of preferentially dropping their packets during times of congestion (http://www.psc.edu/networking/projects/tcpfriendly/) Principles of Congestion Control Informally, congestion entails that too many sources are sending too much data, and sending them too fast for the network to handle. TCP Congestion Control is not the same as flow control, as there are several differences between TCP Congestion Control and flow control. Other principles of congestion control include Global versus point-2-point, and orthogonal issues. Congestion manifests itself by causing loss of packets (buffer overflow at routers), and long delays (queuing in router buffers). Also, during congestion, there is no explicit feedback from network routers, and there is congestion inferred from end-system observed loss. In network-assisted congestion control, routers provide feedback to end systems, and the explicit rate sender sends at –Choke Packet. Below are some other characteristics and principles of congestion control: When CongWin is below Threshold, sender in slow-start phase, window grows exponentially. When CongWin is above Threshold, sender is in congestion-avoidance phase, window grows linearly. When a triple duplicate ACK occurs, Threshold set to CongWin/2 and CongWin set to Threshold. When timeout occurs, Threshold set to CongWin/2 and CongWin is set to 1 MSS. Avoidance of Congestion It is necessary for the TCP sender to use congestion avoidance and slow start algorithms in controlling the amount of outstanding data that is injected into a network. In order to implement these algorithms, two variables are added to the TCP per-connection state. The congestion window (cwnd) is a sender-side limit on the amount of data the sender can transmit into the network before receiving an acknowledgment (ACK), while the receivers advertised window (rwnd) is a receiver-side limit on the amount of outstanding data. The minimum of cwnd and rwnd governs data transmission. (Stevens, W. and Allman, M. 1998) TCP Flow Control In TCP flow control, the receiving side of the TCP connection possesses a receive buffer, and a speed-matching service which matches the send rate to the receiving application’s drain rate. During flow control, Rcvr advertises any spare room by including value of RcvWindow in segments, and the sender limits unACKed data to RcvWindow. TCP flow control also ensures that there is no overflow of the receive buffer. Round-trip Time Estimation and Timeout TCP Round Trip Time and Timeout are usually longer than RTT, but RTT varies, and has a slow reaction to segment loss. SampleRTT is measured time from segment transmission until ACK receipt, ignore retransmissions, and will vary, want estimated RTT â€Å"smoother† Round-trip time samples arrive with new ACKs. The RTT sample is computed as the difference between the current time and a time echo field in the ACK packet. When the first sample is taken, its value is used as the initial value for srtt. Half the first sample is used as the initial value for rttvar. (Round-Trip Time Estimation and RTO Timeout Selection) There are often problems due to timeouts, including the restriction of the sender that is compelled to wait until a timeout, and is able to do nothing during this period. Also, the first segment in the sliding window is often not acked, and retransmission becomes necessary, waiting again one RTT before the segment flow continues. It should be noted that on receiving the later segments, the receiver sends back ACKs. Estimated RTT EstimatedRTT = 0.875 * EstimatedRTT + 0.125 * SampleRTT DevRTT DevRTT = (1 0.25) * DevRTT + | SampleRTT – EstimatedRTT Timeout interval TimeoutInterval = EstimatedRTT + 4 * DevRTT The integrated services (IntServ) and DiffServ (Differentiated Services) architecture are two architectures that have been proposed for the provision of and guaranteeing of quality of service (QoS) over the internet. Whereas the Intserv framework is developed within the IETF to provide individualized QoS guarantees to individual application sessions, Diffserv is geared towards enabling the handling of different classes of traffic in various ways on the internet. These two architectures represent the IETF’s current standards for provision of QoS guarantees, although neither Intserv nor Diffserv have taken off or found widespread acceptance on the web. (a) Integrated Service Architecture In computer networking, the integrated services (IntServ) architecture is an architecture that specifies the elements for the guaranteeing of quality of service (QoS) on the network. For instance, IntServ can be used to allow sound and video to be sent over a network to the receiver without getting interrupted. IntServ specifies a fine-grained Quality of service system, in contrast to DiffServs coarse-grained system of control. In the IntServ architecture, the idea is that each router inside a system implements IntServ, and applications which require various types of guarantees have to make individual reservations. Flow Specs are used to describe the purpose of the reservation, and the underlying mechanism that signals it across the network is called RSVP. TSPECs include token bucket algorithm parameters. The idea is that there is a token bucket which slowly fills up with tokens, arriving at a constant rate. Every packet which is sent requires a token, and if there are no tokens, then it cannot be sent. Thus, the rate at which tokens arrive dictates the average rate of traffic flow, while the depth of the bucket dictates how large the traffic is allowed to be. TSPECs typically just specify the token rate and the bucket depth. For example, a video with a refresh rate of 75 frames per second, with each frame taking 10 packets, might specify a token rate of 750Hz, and a bucket depth of only 10. The bucket depth would be sufficient to accommodate the burst associated with sending an entire frame all at once. On the other hand, a conversation would need a lower token rate, but a much higher bucket depth. This is because there are often pauses in conversations, so they can make do with fewer tokens by not sending the gaps between words and sentences. However, this means the bucket depth needs to be increased to compensate for the traffic being larger. (http://en.wikipedia.org/wiki/Integrated_services) (b) Differentiated Service Architecture The RFC 2475 (An Architecture for Differentiated Services) was published In 1998, by the IETF. Presently, DiffServ has widely replaced other Layer 3 Quality of Service mechanisms (such as IntServ), as the basic protocol that routers use to provide different service levels. DiffServ (Differentiated Services) architecture is a computer networking architecture which specifies a scalable, less complex, coarse-grained mechanism for the classification, management of network traffic and for provision of QoS (Quality of Service) guarantees on modern IP networks. For instance, DiffServ can be used for providing low-latency, guaranteed service (GS) to video, voice or other critical network traffic, while ensuring simple best-effort traffic guarantees to non-critical network services like file transfers and web traffic. Most of the proposed Quality of Service mechanisms which allowed these services to co-exist were complicated and did not adequately meet the demands Internet users because modern data networks carry various kinds of services like streaming music, video, voice, email and also web pages. It would probably be difficult to implement Intserv in the core of the internet because most of the communication between computers connected to the Internet is based on a client/server structural design. This Client/server describes a structure involving the connection of one computer to another for the purpose of giving work instructions or asking it questions. In an arrangement like this, the particular computer that questions and gives out instructions is the client, while the computer that provides answers to the asked questions and responds to the work instructions is the server. The same terms are used to describe the software programs that facilitate the asking and answering. A client application, for instance, presents an on-screen interface for the user to work with at the client computer; the server application welcomes the client and knows how to respond correctly to the clients commands. Any file server or PC can be adapted for use as an Internet server, however a dedicated computer should be chosen. Anyone with a computer and modem can join this network by using a standard phone. Dedicating the server that is, using a computer as a server only helps avoid some security and basic problems that result from sharing the functions of the server. To gain access to the Internet you will require an engineer to install the broadband modem. Then you will be able to use the server to network the Internet on all machines on a network. (www.redbooks.ibm.com/redbooks/pdfs/sg246380.pdf) TASK 5 Network security These days, computers are used for everything from shopping and communication to banking and investment. Intruders into a network system (or hackers) do not care about the privacy or identity of network users. Their aim is to gain control of computers on the network so that they can use these systems to launch attacks on other computer systems. Therefore people who use the network for these purposes must be protected from unknown strangers who try to read their sensitive documents, or use their computer to attack other systems, and send forged email, or access their personal information (such as their bank or other financial statements) Security Clauses The International Organisation for Standardizations (ISOs) 17799: 2005 Standard is a code of practice for information security management which provides a broad, non-technical framework for establishing efficient IT controls. The ISO 17799 Standard consists of 11 clauses that are divided into one or more security categories for a total of 39 security categories The security clauses of the ISO standard 17799:2005- code of practice for Information Security Management include: The security Policy clause Organizing Information Security Asset Management. Human Resources Security. Physical and Environmental Security. Communications and Operations. Access Control. Information Systems Acquisition, Development, and Maintenance. Information Security Incident Management. Business Continuity Management. Compliance. (http://www.theiia.org/ITAuditArchive/index.cfm?act=ITAudit.printiiid=467aid=2209) Here is a brief description of the more recent version of these security clauses: Security Policy: Security policies are the foundation of the security framework and provide direction and information on the companys security posture. This clause states that support for information security should be done in accordance with the companys security policy. Organizing Information Security: This clause addresses the establishment and organizational structure of the security program, including the appropriate management framework for security policy, how information assets should be secured from third parties, and how information security is maintained when processing is outsourced. Asset Management: This clause describes best practices for classifying and protecting assets, including data, software, hardware, and utilities. The clause also provides information on how to classify data, how data should be handled, and how to protect data assets adequately. Human Resources Security: This clause describes best practices for personnel management, including hiring practices, termination procedures, employee training on security controls, dissemination of security policies, and use of incident response procedures. Physical and Environmental Security: As the name implies, this clause addresses the different physical and environmental aspects of security, including best practices organizations can use to mitigate service interruptions, prevent unauthorized physical access, or minimize theft of corporate resources. Communications and Operations: This clause discusses the requirements pertaining to the management and operation of systems and electronic information. Examples of controls to audit in this area include system planning, network management, and e-mail and e-commerce security. Access Control: This security clause describes how access to corporate assets should be managed, including access to digital and nondigital information, as well as network resources. Information Systems Acquisitions, Development, and Maintenance: This section discusses the development of IT systems, including applications created by third-parties, and how security should be incorporated during the development phase. Information Security Incident Management: This clause identifies best practices for communicating information security issues and weaknesses, such as reporting and escalation procedures. Once established, auditors can review existing controls to determine if the company has adequate procedures in place to handle security incidents. Business Continuity Management: The 10th security clause provides information on disaster recovery and business continuity planning. Actions auditors should review include how plans are developed, maintained, tested, and validated, and whether or not the plans address critical business operation components. Compliance: The final clause provides valuable information auditors can use when identifying the compliance level of systems and controls with internal security policies, industry-specific regulations, and government legislation. (Edmead, M. T. 2006 retrieved from http://www.theiia.org/ITAuditArchive/?aid=2209iid=467) The standard, which was updated in June 2005 to reflect changes in the field of information security, provides a high-level view of information security from different angles and a comprehensive set of information security best practices. More specifically, ISO 17799 is designed for companies that wish to develop effective information security management practices and enhance their IT security efforts. Control Objectives The ISO 17799 Standard contains 11 clauses which are split into security categories, with each category having a clear control objective. There are a total of 39 security categories in the standard. The control objectives in the clauses are designed to meet the risk assessment requirements and they can serve as a practical guideline or common basis for development of effective security management practices and organisational security standards. Therefore, if a company is compliant with the ISO/IEC 17799 Standard, it will most likely meet IT management requirements found in other laws and regulations. However, because different standards strive for different overall objectives, auditors should point out that compliance with 17799 alone will not meet all of the requirements needed for compliance with other laws and regulations. Establishing an ISO/IEC 17799 compliance program could enhance a companys information security controls and IT environment greatly. Conducting an audit evaluation of the standard provides organizations with a quick snapshot of the security infrastructure. Based on this snapshot, senior managers can obtain a high-level view of how well information security is being implemented across the IT environment. In fact, the evaluation can highlight gaps present in security controls and identify areas for improvement. In addition, organizations looking to enhance their IT and security controls could keep in mind other ISO standards, especially current and future standards from the 27000 series, which the ISO has set aside for guidance on security best practices. (Edmead, M. T. 2006 retrieved from http://www.theiia.org/ITAuditArchive/?aid=2209iid=467) Tree Topology Tree topologies bind multiple star topologies together onto a bus. In its most simple form, only hub devices are directly connected to the tree bus and the hubs function as the root of the device tree. This bus/star hybrid approach supports future expandability of the network much better than a bus (limited in the number of devices due to the broadcast traffic it generates) or a star (limited by the number of hub ports) alone. Topologies remain an important part of network design theory. It is very simple to build a home or small business network without understanding the difference between a bus design and a star design, but understanding the concepts behind these gives you a deeper understanding of important elements like hubs, broadcasts, ports, and routes. (www.redbooks.ibm.com/redbooks/pdfs/sg246380.pdf) Use of the ring topology should be considered for use in medium sized companies, and the ring topology would also be the best topology for small companies because it is ensures ease of data transfer. Ring Topology In a ring network, there are two neighbors for each device, so as to enable communication. Messages are passed in the same direction, through a ring which is effectively either counterclockwise or clockwise. If any cable or device fails, this will break the loop and could disable the entire network. Bus Topology Bus networks utilize a common backbone to connect various devices. This backbone, which is a single cable, functions as a shared medium of communication which the devices tap into or attach to, with an interface connector. A device wanting to communicate with another device on the network sends a broadcast message onto the wire that all other devices see, but only the intended recipient actually accepts and processes the message. (www.redbooks.ibm.com/redbooks/pdfs/sg246380.pdf) Star Topology The star topology is used in a lot of home networks. A star network consists of a central connection point or hub that can be in the form of an actual hub, or a switch. Usually, devices will connect to the switch or hub by an Unshielded Twisted Pair (UTP) Ethernet. Compared to the bus topology, a star network generally requires more cable, but a failure in any star network cable will only take down one computers network access and not the entire LAN. If the hub fails, however, the entire network also fails. (www.redbooks.ibm.com/redbooks/pdfs/sg246380.pdf) Relating the security clauses and control objectives to an organisation In an organisation like the Nurht’s Institute of Information Technology (NIIT), the above mentioned security clauses and control objectives provide a high-level view of information security from different angles and a comprehensive set of information best security practices. Also, the ISO 17799 is designed for companies like NIIT, which aim to enhance their IT security, and to develop effective information security management practices. At NIIT, the local network relies to a considerable degree, on the correct implementation of these security practices and other algorithms so as to avoid congestion collapse, and preserve network stability. An attacker or hacker on the network can cause TCP endpoints to react in a more aggressive way in the face of congestion, by the forging of excessive data acknowledgments, or excess duplicate acknowledgments. Such an attack could possibly cause a portion of the network to go into congestion collapse. The Security Policy clause states that â€Å"support for information security should be done in accordance with the companys security policy.† (Edmead, M. T. 2006). This provides a foundation of the security framework at NIIT, and also provides information and direction on the organisation’s security posture. For instance, this clause helps the company auditors to determine whether the security policy of the company is properly maintained, and also if indeed it is to be disseminated to every employee. The Organizing Information Security clause stipulates that there should be appropriate management framework for the organisation’s security policy. This takes care of the organizational structure of NIIT’s security program, including the right security policy management framework, the securing of information assets from third parties, and the maintenance of information security during outsourced processing. At NIIT, the Security clauses and control objectives define the company’s stand on security and also help to identify the vital areas considered when implementing IT controls. The ISO/IEC 17799s 11 security clauses enable NIIT to accomplish its security objectives by providing a comprehensive set of information security best practices for the company to utilize for enhancement of its IT infrastructure. Conclusion Different businesses require different computer networks, because the type of network utilized in an organisation must be suitable for the organisation. It is advisable for smaller businesses to use the LAN type of network because it is more reliable. The WAN and MAN would be ideal for larger companies, but if an organisation decides to expand, they can then change the type of network they have in use. If an organisation decides to go international, then a Wireless Area Network can be very useful Also, small companies should endeavor to set up their network by using a client/server approach. This would help the company to be more secure and enable them to keep in touch with the activities of others are doing. The client/server would be much better than a peer-to-peer network, it would be more cost-effective. On the average, most organisations have to spend a good amount of money and resources to procure and maintain a reliable and successful network that will be and easy to maintain in the long run. For TCP Congestion Control, when CongWin is below Threshold, sender in slow-start phase, window grows exponentially. If CongWin is above Threshold, sender is in congestion-avoidance phase, window grows linearly. When a triple duplicate ACK occurs, Threshold set to CongWin/2 and CongWin set to Threshold, and threshold set to CongWin/2 and CongWin is set to 1 MSS when a timeout occurs. For a Small Office/Home Office (SOHO), networks such as wireless networks are very suitable. In such a network, there won’t be any need to run wires through walls and under carpets for connectivity. The SOHO user need not worry about plugging their laptop into docking stations every time they come into the office or fumble for clumsy and unattractive network cabling. Wireless networking provides connectivity without the hassle and cost of wiring and expensive docking stations. Also, as the business or home office grows or shrinks, the need for wiring new computers to the network is nonexistent. If the business moves, the network is ready for use as soon as the computers are moved. For the wired impossible networks such as those that might be found in warehouses, wireless will always be the only attractive alternative. As wireless speeds increase, these users have only brighter days in their future. (http://www.nextstep.ir/network.shtml) It is essential to note that the computer network installed in an organisation represents more than just a simple change in the method by which employees communicate. The impact of a particular computer network may dramatically affect the way employees in an organisation work and also affect the way they think. Bibliography Business Editors High-Tech Writers. (2003, July 22). International VoIP Council Launches Fax-Over-IP Working Group. Business Wire. Retrieved July 28, 2003 from ProQuest database. Career Directions (2001 October). Tech Directions, 61(3), 28 Retrieved July 21, 2003 from EBSCOhost database Edmead, M. T. (2006) Are You Familiar with the Most Recent ISO/IEC 17799 Changes? (Retrieved from http://www.theiia.org/ITAuditArchive/?aid=2209iid=467) FitzGerald, J. (1999), Business Data Communications And Networking Pub: John Wiley Sons Forouzan, B. (1998), Introduction To Data Communications And Networking Pub: Mc- Graw Hill http://www.theiia.org/itaudit http://www.theiia.org/ITAuditArchive/index.cfm?act=ITAudit.printiiid=467aid=2209 http://www.psc.edu/networking/projects/tcpfriendly/ ISO/IEC 17799:2000 – Code of practice for information security management Published by ISO and the British Standards Institute [http://www.iso.org/] ISO/IEC 17799:2005, Information technology – Security techniques – Code of practice for information security management. Published by ISO [http://www.iso.org/iso/en/prods-services/popstds/informationsecurity.html] Kurose, J. F. Ross, K. W. 2002. Computer Networking A Top-Down Approach Featuring the Internet, 2nd Edition, ISBN: 0-321-17644-8 (the international edition), ISBN: 0-201-97699-4, published by Addison-Wesley, 2002 www.awl.com/cs Ming, D. R. Sudama (1992) NETWORK MONITORING EXPLAINED: DESIGN AND APPLICATION Pub: Ellis Horwood Rigney, S. (1995) NETWORK PLANNING AND MANAGMENT YOUR PERSONAL CONSALTANT Round-Trip Time Estimation and RTO Timeout Selection (retrieved from http://netlab.cse.yzu.edu.tw/ns2/html/doc/node368.html) Shafer, M. (2001, June 11). Careers not so secure? Network Computing, 12(12), 130- Retrieved July 22, 2003 from EBSCOhost database Stevens, W. and Allman, M. (1998) TCP Implementation Working Group (retrieved from http://www.ietf.org/proceedings/98aug/I-D/draft-ietf-tcpimpl-cong-control-00.txt) Watson, S (2002). The Network Troubleshooters. Computerworld 36(38), 54. (Retrieved July 21, 2003 from EBSCOhost database) Wesley, A. (2000), Internet Users Guide to Network Resource Tools 1st Ed, Pub: Netskils www.microsoft.co.uk www.apple.com www.apple.co.uk www.bized.com http://www.nextstep.ir/network.shtml www.novell.com www.apple.com/business www.microsoft.com/networking/e-mails www.engin.umich.edu www.microsoft.com

Motivation in the Classroom Essay -- Teaching Education

Motivation in the Classroom Students want and need work that enables them to demonstrate and improve their sense of themselves as competent and successful human beings. This is the drive toward mastery. But success, while highly valued in our society, can be more or less motivational. People who are highly creative, for example, actually experience failure far more often than success. Biehler (p. 225) claims that studies show that when CAI used in conjunction with a teacher's lessons, is particularly beneficial for low-achieving and young students. Before we can use success to motivate our students to produce high-quality work, we must meet three conditions: 1. We must clearly articulate the criteria for success and provide clear, immediate, and constructive feedback. 2. We must show students that the skills they need to be successful are within their grasp by clearly and systematically modeling these skills. 3. We must help them see success as a valuable aspect of their personalities. All this seems obvious enough, but it is remarkable how often we fail to meet these conditions for our students. Take skills. Can you remember any crucial skills that you felt you did not successfully master because they were not clearly taught? Was it finding themes in literature? Reading and interpreting primary texts? Thinking through nonroutine math problems? Typically, skills like these are routinely assigned or assumed, rather than systematically modeled or practiced by teachers. So how can we help students master such skills? When teaching your students to find themes, for example, deliberately model interpretation. Ask your students to give you a poem you have never seen, and then interpret it both for and with them. If they are reading primary texts, use what we call the "main idea" strategy. Teach them how to find the topic (usually a noun or noun phrase), the main idea (a sentence that states the text's position on the topic), and reasons or evidence to support the main idea. If students are concerned about writer's block, remember that perhaps the most difficult task of a teacher is to teach how to think creatively. In regards to behavior modification it's noted in Biehler(p.237), in the case of primary students there is a possibility that some students will come to realize that the teacher rewards them only when they've done what she... ... arouses intense curiosity? By making sure it features two defining characteristics: the information about a topic is fragmentary or contradictory, and the topic relates to students' personal lives. Students then work together in-groups, retracing the steps scientists took in weighing the available evidence to arrive at an explanation. We have seen student’s work diligently for several days dealing with false hypotheses and red herrings, taking great delight when the solutions begin to emerge. As for topics that relate to students' lives, the connection here cannot be superficial; it must involve an issue or idea that is both manageable and unresolved. We must ask, With what issues are adolescents wrestling? How can we connect them to our curriculum? Figure 1 illustrates some possibilities for adolescents. Bibliography: References Snowman, Jack/Biehler, Robert (2000) Psychology Applied to Teaching Houghton Mifflin Co. Colin, Baker (1996) Foundations of Bilingual Education and Bilingualism Multilingual Matters (pgs 105-143) Cummins, Jim (1996) Negotiating Identities: Education for Empowerment in a Diverse Society California Association for Bilingual Education

My Summer Vacation Essay

Relaxing out in the sun in the middle of a lake that stretches for miles and miles, is probably one of the most amazing things you could ever see in life. The best part about that, I get to enjoy that every summer. Every summer my family goes to a small cabin on Lake Rainy in Canada. The most memorable time I have ever had with my family was at our family cabin in Canada. It was the summer of 2007 and also one of the hottest trips we’ve had at our cabin. One of my favorite things about the cabin is that it has no electricity unless we have the generator on. My brothers whined about that for the first couple days! Bubba even tried to convince Aunt Linda to turn on the generator just so he could watch a movie. With no success with my aunt he asked Uncle Tom and got his way. After the kids got the idea that there would be no more turning the generator on for little things like charging their Game Boys, things actually started to get better. With almost all technology set aside we did things unheard of in this day in age. One night we decided we were tired of being bored and I thought my little brother to play Kings Corner, they didn’t like that game very much. I decided it was time for a little easier game; it would have to be easy to catch Bubba’s attention. Uno was the game we played most nights. Playing Uno at the cabin was great, the entire family was ordered to play by my Aunt Linda and since she is the boss, no one would have even thought otherwise. Don’t get me wrong we didn’t spend all of our time indoors. We went swimming very frequently, most of the time just to stay cool. It was usually too hot to go fishing, unless you had a death wish. One day when it was cool enough to fish, Kelsey caught the most beautiful Walleye I have ever seen. My little cousin Kimmy wasn’t to excited about eating fish so the made her chicken every night we had fish. (This was most nights. ) The only thing I hated about Canada honestly was leaving. On the last day we’re at the cabin everyone is usually pretty sad to be leaving. It was always nice to get home, but as soon as we would get home we would instantly start to miss watching the sunset on a lake that stretched for miles and miles.

Online Dating Advantages

Some advantages and disavantages in online dating. Now days online dating hvae become so commun that everyone know a site or two where can meet or interact with other people becoming making it easy to become part of the online dating trend. But veryb seldon anyone couciously stop to think and anlyze the advantages or disavantages in online dating. In today's world everything goes so fast that it seem's 24 hour days are over for ever, every one is short of time.People running to school, work, appointments, that realistically there is no time to just go out to socialized and interact with friends or just go out. Online Dating, have filled this human need to be loved or wanted by some one else by just flipping tha computer switch or pushing a button. Instantly you have complete access to online world that where you can shoose to be part of to share your momories, fotos,tastes, likes and dislikes to the world. There are two words that plays a key role to the online dating phenomenun; fre e and instantly.You can freely bacome part of a online community and instatly intereract with those that accept you all for free, bringing this interaction up to your creativity and inmagination to meet as many and different people you would like. Even though, it can be very advantegeous to meet new people online and date,there are deffenetelly some important disavantages to consider. Online dating make it for the most part very easy to interact with so many people at differente place at different time , that you are constantly bonbard with a lot of possibilities.You can date someone today and tomrrow you could date someone else. According to a survey done by fox news, 60 % of online dating participants are actually dating two or more person at the same time. According to the report most people that are engage in online dating, feel that online is just another world , another set of values, nothing like could be judge as real. Moral and values that tend to be pracitce when meeting s omeone on a local school or live occassion wouldn't apply to those people met online.For one reason or another, online Dating keep beeing a growing trend, more youngster then ever have access to the internet and actually interacting with others on social sites and dating sites. With advantages and Disavantages today many online users are just so accostome to the online world that they have not even consider any dissavantages since its have just become a way of life. Online dating will continue benefiting those users that engage in an intelligente mature way or disgracing those that have poor judgment.