Computational thinking

Question 1

What is abstraction?

Answer 1

• The removal of unnecessary details in a problem

Question 2

What is decomposition?

Answer 2

• Breaking down a problem into smaller chunks / sub-problems

Question 3

What are pre-conditions?

Answer 3

• Conditions that must be true for an algorithm to complete succesfully, without errors or crashing

Question 4

How is abstraction used in the London Underground?

Answer 4

• Travellers do not need to know the geographical layout of the train stations
• They only need to know what order the stops are in

Question 5

What is a top-down design?

Answer 5

• Involves breaking down a problem into major tasks and then breaking down these major tasks into smaller sub-problems
• Each sub-problem is broken down until it can be solved using a single sub-routine or module

Question 6

What are the advantages of decomposing a problem?

Answer 6

• Each sub-routine is easier to test and maintain
• Each sub-routine is self-contained and well-documented, making it easier to find errors in code and fix problems as they arise
• Convenient to reuse sub-routines

Question 7

What is a hierarchy chart?

Answer 7

• An example of a diagram used to show problem decomposition
• Each problem is divided into multiple sub-problems, which are then divided into further sub-problems

Question 8

What are structured programming techniques?

Answer 8

• Sequence: one statement after another
• Selection: decision making, if/else/elif
• Iteration: loops, for/while/do while

Question 9

What is the point of structured programming techniques?

Answer 9

• To aid readability, understanding and maintainability of code

Question 10

What is concurrent and parallel computing?

Answer 10

• Concurrent computing allows multiple processes/tasks to run on a single processor by giving each process a fraction of time and control over the processor before swapping to another process
• Parallel processing is when multiple processes are run at the same time over multiple processor cores to enable faster computations

Question 11

What are dependencies?

Answer 11

• Tasks that rely on other tasks in order to either start or complete

Question 12

What is concurrent processing?

Answer 12

• Allows multiple processes to run on a single processor
• Gives each process a fraction of time and control over the processor before swapping to another process

Question 13

Pros and cons of concurrent processing

Answer 13

• Pros: number of tasks completed in a timeframe increases, time spent waiting for user input is minimised by swapping to another task
• Cons: if large numbers of processes are running that involve high quantities of computation, they will take longer as they only get allocated a specific time frame

Question 14

Pros and cons of parallel processing

Answer 14

• Pros: can speed up tasks by splitting processes over several processors, 3d objects can be rendered quickly by splitting over processors, multiple different programs can run at the same time using different processors
• Cons: different tasks on different processors may need to communicate leading to delays, some tasks may run faster on a single processor (optimised)