1.2 System Design Basics
Interestingly (strangely?) the IB Computer Science subject guide doesn't make any mention of System Development Life Cycle (SDLC), but it does include components of each major step. These are spread between this section (1.1 Systems in Organisations) and 1.2 (System Design Basics). This section covers issues which are more user-oriented and related to the actual implementation of IT systems.
Click here for recommended IB Computer Science textbooks.Components of a computer system
1.2.2 Roles within a networked world
What Happens When You Click a Link?
This video explains step by step what happens when you enter a URL in your web browser. It covers looking up the IP address using the HOSTS file or DNS, connecting to the destination machine using TCP/IP, and using HTTP to fetch the page. It does a good job of breaking down the process into a series of simple steps that demystify this process for students (hopefully!).
How the DNS works
An animation showing how DNS works when you type the URL of a website into your web browser. This video goes into more detail than some of the others here, showing how a computer locates nameservers before finding the IP address of a domain name. Useful for older students.
DNS Explained
This video goes into a LOT of detail about DNS and the different types of nameservers: the root nameservers, the TLD nameservers, and authoriative name servers. This is probably more detail than most students will need, but it can help understand the bigger picture, so is included here.
1.2.4 Planning a new system
Software Development Lifecycle in 9 minutes!
This is quite an entertaining overview of the SDLC, with clear examples of what happens at each stage. Note that the stages in the SDLC are broken down in different ways by different people (for example, here they count planning and analysis as two separate stages - often they are incorporated into one). However, the content is sound and highlights the need for clear boundaries between the tasks in each stage.
1.2.12 - 1.2.15 Usability and Accessibility
Human Computer Interaction (HCI)
This page has very detailed notes on many human-computer interaction and usability issues. It has excellent interactive examples of bad user interfaces and the mistakes that software and hardware developers often make, including information about mode errors, user feedback, consistency, and error prevention. It also has links to further reading about HCI theory and design rules.
Psychology of Computing
This video examines the issue of computer usability. It is full of great examples of user interface design, and explains the reasons behind them. Many of the items mentioned in the video are so common that we barely notice them in our daily lives, but the video links these choices to human psychology and our understanding of the real world.
1.2.16 Moral, ethical, social, economic, and environmental implications
Environmental Impacts of Computing
The Story of Electronics and the High Tech Trash quiz make good lesson starters.
Several photo essays are available online which highlight the problems caused by electronic waste:
The toxic chemicals found in e-waste are explained by National Geographic and GreenPeace.
NSA Internet surveillance
In June 2013, the Guardian and Washington Post newspapers published revelations about a secret, quasi-legal US government Internet surveillance programme known as PRISM and operated by the National Security Agency (NSA). In the following weeks global media continued publishing revelations of ever more extraordinary surveillance systems. First, revelations that the NSA had worked with the British intelligency agency GCHQ to side-step legal issues, then evidence that online images were being collected and mined, and finally, confirmation that thousands of mobile phones had been monitored and tracked. Foreign allies were quickly alienated as it was revealed that the NSA had spied on supposedly friendly governments and ministers, including the Germans, Chileans, and Brazilians. The articles below highlight some of the key events in the scandal, and make excellent material for classroom discussion of the ethics of surveillance.
- The NSA and surveillance ... made simple - video animation
- NSA Prism program taps in to user data of Apple, Google and others
- GCHQ taps fibre-optic cables for secret access to world's communications
- NSA 'tracking' hundreds of millions of mobile phones
- New NSA leaks show how US is bugging its European allies
- US allies Mexico, Chile and Brazil seek spying answers
- NSA monitored calls of 35 world leaders
- NSA collects millions of text messages daily in 'untargeted' global sweep
- N.S.A. Collecting Millions of Faces From Web Images (NY Times)
- What the NSA can (and can't) mine from intercepted photos
- NSA: Nude Snaps Agency - Swapping other people's sexts is a fringe benefit
Enemy of the State DVD
Many of the surveillance technologies and methods featured in Enemy of the State - which features Will Smith as a lawyer tracked down by government agents - may seem pure fantasy. However, recent revelations about NSA spying once again make this a relevant and pertinent film that deals with contemporary issues.
United States of Secrets
A compelling two-part PBS documentary about the US government (and particularly the NSA's) warrantless surveillance of the Internet of millions, which was only revealed after Edward Snowden leaked classified information
The documentary does a good job of addressing both sides of the surveillance argument, featuring interviews with government insiders, including those who were the architects of the now infamous surveillance systems.
Watch the documentary on the PBS website
Ethics in Computing
Ethics in Computing covers a wide range of ethical situations from intellectual property to free speech and privacy. Different areas are covered - including government, medical, and educational. Each section is subdivided and has a plethora of links to case studies or news articles. This means some work is needed to find the most relevant articles, and the site itself is probably better suited to older students.