Unit 10 Computational Thinking

Question 1

What is Abstraction?

Answer 1

A way of separating the logical and physical aspects of a problem such as removing less relevant parts of a problem

Question 2

What are the advantages of specifying preconditions? (3)

Answer 2

• Clearly documenting preconditions helps to make the function reusable
• Cuts out unnecessary checks
• Makes the program shorter which helps to speed up debugging and maintenance

Question 3

What are some typical standards for Reusable Modules? (6)

Answer 3

• Inputs, outputs and preconditions should be documented
• Variable identifiers should conform to a standard convention
• All variables must be local to the module
• Documentation should be in a standard format, explaining what the module does, who it was written by, date it was written
• Explanations of certain sections of code should be included where necessary
• No module should exceed one page of code

Question 4

Why do Reusable Modules need to conform to certain programming standards?

Answer 4

To make them easy to use for other programmers

Question 5

What is Caching?

Answer 5

Caching is the temporary storage of data and instructions. The last few instructions of a program or frequently used data could be stored

Question 6

What are the advantages of Caching? (3)

Answer 6

• Faster access to cached resources
• Saving on costly use of bandwidth
• Reduced load on web services in a client-server environment

Question 7

What is a disadvantage of Caching?

Answer 7

Slower performance if the resource isn’t found in the cache

Question 8

What is Procedural Decomposition?

Answer 8

Procedural decomposition means breaking a problem into a number of sub-problems, so that each sub-problem accomplishes an identifiable task

Question 9

What is Modularization for?

Answer 9

Program structure and organization, i.e. breaking the problem down into subroutines

Question 10

What are the advantages of Modularization? (5)

Answer 10

• Large programs are broken down into subtasks/subroutines that are easier to program and manage
• Each subroutine can be individually tested
• Modules can be re-used several times in a program
• Frequently used modules can be saved in a library and used by other programs
• Several programmers can simultaneously work on different modules, shortening development time

Question 11

What are features of good programming practice? (5)

Answer 11

• Use meaningful identifiers
• Define and document the inputs, outputs and preconditions for each sub-procedure
• Add lots of meaningful comments within the program
• At the bottom level, each sub-procedure should perform a single task
• Keep each sub-procedure self-contained by passing parameters and using local variables

Question 12

What are features of a good algorithm? (5)

Answer 12

• Has clear and precisely stated steps that produce the correct output for any set of valid inputs
• Should allow for invalid inputs
• Must always terminate at some point
• Should execute efficiently, in as few steps as possible
• Should be designed in such a way that other people will be able to understand it and modify it if necessary

Question 13

What is hand-tracing useful for? (2)

Answer 13

• Figuring out how an algorithm works
• Finding out why an algorithm is not working properly

Question 14

What happens in Concurrent Processing?

Answer 14

Multiple processors execute instructions simultaneously
Tasks are broken down into sub-tasks that can be assigned to separate processors to perform simultaneously

Question 15

What is Simulation?

Answer 15

The process of designing a model of a real system in order to understand the behaviour of the system, and to evaluate various strategies for its operation