2.1 Elements of computational thinking

Question 1

What is abstraction?

Answer 1

removing information that is too complex or irrelevant to the system’s purpose (unnecessary detail)

Question 2

Why is abstraction needed? (3)

Answer 2

-enables for efficient software design as programmers can focus on core features instead of unnecessary details
-reduces time spent on a project
-saves memory space

Question 3

What is an example of abstraction?

Answer 3

TCP/IP model
-abstraction of how networks function
-separated into four simple layers
-each layer deals with a different part of the communication process
-doesn’t need to know how other layers function

Question 4

What are the different ways projects can be abstracted?

Answer 4

-representational
-data
-layered
-generalisation
-procedural

Question 5

Explain representational abstraction

Answer 5

-removing unnecessary details to represent a problem using only the key features
-must analyse what is relevant to a scenario and simplify a problem based on this

Question 6

Explain data abstraction

Answer 6

-details about how data is being stored are hidden
-programmers can use data structures without knowing how they are implemented

Question 7

Explain layered abstraction. Give an example of this

Answer 7

-large, complex problems are split into layers of abstraction
-each layer has a different role, with the highest layers being closest to the user
-these are usually responsible for providing a user interface
-the lowest levels perform tasks such as interacting with machine components

example of this is the TCP/IP model

Question 8

Explain abstraction by generalisation

Answer 8

-grouping together similarities within a problem to identify what kind of problem
-allows problems to be categorised as being of a particular type
-a common solution can be used to solve these problems

Question 9

Explain procedural abstraction

Answer 9

-allows programmers to utilise functions without knowing how they are implemented
-used in decomposition and manipulating data structures
-models what a subroutine does without considering how, as once a subroutine has
been written, it can be reused as a black-box

Question 10

What should we think about when needing to devise an abstract model for scenarios? (4)

Answer 10

-what is the problem that needs to be solved by the model?
-how will the model be used?
-who will the model be used by?
-which parts of the problem are relevant based on the target audience and purpose
of the model?

Question 11

Why is thinking ahead useful?

Answer 11

makes development easy and programs can be built to be intuitive

Question 12

What are inputs?

Answer 12

data required to solve the problem (data entered into the system by the user)

Question 13

What are outputs?

Answer 13

results passed back to the user

Question 14

What are some ways of thinking ahead? Why are these useful? (3)

Answer 14

-creating preconditions (requirements which must be met before a program can be executed)
reduces length and complexity of programs
saves time spent on debugging and maintenance

-creating reusable program components (using libraries or subroutines)
saves time
increases development efficiency
reliable

-caching (storing instructions/data in cache memory after they’ve been used, as they could be used again)
saves time instead of going to secondary storage
frees up bandwidth
less time to fetch

Question 15

What do we mean by thinking procedurally?

Answer 15

breaking down a complex problem then thinking logically and sequentially to find a solution

Question 16

Explain the first stage of thinking procedurally. What are some positives to doing this?

Answer 16

problem decomposition

breaking a large complex problem into smaller subproblems which can be solved more easily
-easier to manage
-subproblems can be divided within a team
-subproblems can be tested separately, so are self-contained

Question 17

What is the second stage of thinking procedurally? What do we need to consider?

Answer 17

considering each component and using them to build up a solution

-can this be implemented as a function or a procedure?
-what inputs are required?
-what output does the subroutine need to produce?

Question 18

What do we mean by thinking logically?

Answer 18

analysing a situation or problem using reason and coming up with potential solutions

Question 19

What are some questions needed to be evaluated when thinking logically?

Answer 19

-what is most effective?
-what is most convenient?
-is this option reasonable?

Question 20

How can we think logically? (2)

Answer 20

use procedural thinking
using flowcharts to find different outcomes of a problem

Question 21

What do we mean by thinking concurrently?

Answer 21

the process of completing more than one task at a given time

-involves giving time ‘slices’ to different tasks

Question 22

Compare concurrent and parallel processing

Answer 22

concurrent- each task is given a slice of processor time to make it
appear as if tasks are being completed simultaneously

parallel- when multiple processors are used to complete more than
one task simultaneously

Question 23

Why is concurrent processing useful?

Answer 23

-the number of tasks completed in a given time is increased
-less time is wasted waiting for an input or user interaction (other tasks can be completed in this time)

Question 24

What are some drawbacks to concurrent processing?

Answer 24

-can take longer to complete when large numbers of users/tasks involved
-an overhead in coordinating and switching between processes (reduces program throughput)
-not all tasks are suited to being broken up and performed concurrently