Computer Science Analysis

Analyse an area of computer science

Digital Technologies | Level 3 | AS 91908 (3.9) | 3 Credits

*** In 2025 this external will be an Online Examination held on WEDNESDAY 12th NOVEMBER - PM ***

WHAT IS THIS STANDARD ABOUT?

This exam asks students to analyse a specific area of computer science. Students need to go beyond just describing the topic, they need to explain how it works, explore real-world examples, discuss its challenges, and evaluate its impact from different perspectives.

This is a chance to show not just what they know, but how well you can think critically about a complex computer science idea.

Every year, THREE topics are named in the NZQA Assessment Specifications for Teachers and Students to focus on. In the exam students choose to answer questions for ONE topic only.

In 2025 the THREE topics are: Complexity and tractability, Computer vision, Computer graphics

From the NZQA 91908 Assessment Specifications 2025:

Candidates will be required to respond in short and / or extended answers (800–1500 words in total) to questions relating to their choice of ONE of the following computer science concepts:

Complexity and tractability
Computer vision
Computer graphics.

For Complexity and tractability, questions may cover: polynomial and non-polynomial time complexity, Big O notations O(1), O(log n), O(n) , O(n^k), O(2^n), O(n!), and best-case, worst-case, and average-case time complexity, complexity classes (P, NP, NP-complete), solving complex problems (approximation algorithms / heuristics), algorithm design and optimisation, optimal solutions (Travelling Salesman / knapsack, etc.).

For computer vision, questions may cover: noise, thresholding, edge detection, image processing for computer vision, applications in fields of obstacle detection (e.g. Lidar and stereo vision), feature extraction (e.g. Viola Jones, Haar-like features) and medical detection, and the application of techniques to medical diagnosis (e.g. convolutional neural networks, decision trees, and random forests).

For computer graphics, questions may cover: bitmap and vector graphics, matrices and transformations, line and circle algorithms (e.g. Bresenham's line algorithm, midpoint circle algorithm), image rendering (raytracing vs rasterisation), texture mapping, lighting, and lighting effects and reflections.

Special notes:

Teachers are encouraged to help their students to develop answering techniques to ensure that they are able to respond clearly and concisely within the total recommended word limit. Responses that exceed this may not be considered for assessment past the 1500-word limit.
Teachers are strongly encouraged to prepare students to be able to apply their understanding of computer science to unfamiliar contexts.
Teachers should prepare students to identify and articulate instances where overlap with various areas of computer science occurs, e.g. with artificial intelligence.

RESOURCES FOR L3 COMPUTER GRAPHICS

Task 1 - What is Computer Graphics

First you need to understand what Computer Graphics entails.

The GOAT: The CSField Guide: Computer Graphics Watch the video and read through the material. If you learn this stuff inside out and you'll smash it.

This powerpoint covers the whole teaching and learning materials

Computer Graphics Year 13.pptx

Task 2 - Really Understand Vector vs Raster

You should have already read through this in the task above but you really need to understand vector vs raster, the similarities and differences.

https://www.csfieldguide.org.nz/en/chapters/computer-graphics/drawing-lines-and-circles/

Task 3 - Really Understand Computer Graphics Transformations

Scaling rotation, translation, Focus on translation

Complete the Year 13 Worksheet transformations. https://www.csfieldguide.org.nz/en/chapters/computer-graphics/graphics-transformations/
Then complete these interactivc tasks

Task 4 - Really Understand Computer Lines

Bresenhams Line algorithm. The videos below will help support your understanding.

You need to be able to do it :

https://www.csfieldguide.org.nz/en/chapters/computer-graphics/drawing-lines-and-circles/#line-drawing

Task 5 - What the markers are looking for....

--- COMMENTS FROM THE 2022 DCAT --- (drop down)

Candidates’ knowledge and understanding of content, skills, and complexities must be at Level 8 of the New Zealand Curriculum.

Candidates who had a comprehensive understanding of computer science, or had completed an authentic and appropriately levelled project, were able to apply their knowledge and achieve well.

Candidates who lacked confidence with the material tended to either repeat their answers without adding information or were unable to provide a sufficient response.

Candidates who were able to give clear explanations and make links to examples, or who referenced their project work thoroughly, achieved higher grades than those who wrote indiscriminately or without precision.

Candidates who understood the content of their chosen topic, or who understood the intricacies of their decision-making processes, tended to write more succinct and relevant responses. Students who attempted to write as much as possible to answer a question often ended up demonstrating a lack of understanding or a lack of good decision-making in their workflows.

Candidates were required to choose a question on one of three areas of computer science (formal languages, computer graphics, and computer vision). Resource materials were provided to support the questions.

Candidates needed to understand the computer science components of the topic they intended to answer, and to be familiar with how to explain these computer science fundamentals.

Candidates who appeared unfamiliar with the underlying computer science struggled to understand or answer the questions at the level required.

Candidates that answered questions without specific reference to algorithms or techniques involved were unable to demonstrate understanding. Each question followed the same general format:

the initial part required candidates to accurately apply their understanding of the basic concepts of each topic, either by determining sequence outcomes or concisely explaining relevant concepts and then demonstrating how they determined their answer
the later part required candidates to consider the impact of the concept on humans and perspectives around the concepts, using resource materials provided
the final part asked candidates to answer in a more in-depth way and to provide justification or reasoning. Teachers should refer to accurate guidance resources to support their candidates’ learning. For example, The Computer Science Field Guide is an online interactive resource for high school candidates learning about computer science. https://www.csfieldguide.org.nz/.

Check out the 91908 Assessment Report 2022 if you want some more specifics about what was done to meet each level of achievement.

Task 6 - Practice Task

You may have already completed this. Go back and have a look at what your answers were. Or have another go. (don't worry about circle)

Are there any gaps? Have you taken on the markers comments?

To be successful you must be able to do:

Transformations: Translation Scaling Rotation: Similarities and Differences
How would these be used by people and affect people positive and negative.
How are computer graphics changing the way we live and work look up examples

BHS DCAT DERIVED GRADE EXAM

Term 3 Week 6 (During School Exams)

(you will see each course is timetabled 13DTE, 13DTG, 13DTM, 13DTP)

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