Edexcel GCSE Computer Science, Unit 1: Computational Thinking

Algorithm

Set of step-by-step instructions to complete a task, or solve a problem

Decomposition

Break down a problem into smaller sub-problems

Abstraction

Remove unnecessary information from a problem

Pattern recognition

Seeing similarities and differences in a range of problems

Computational thinking

Using methods to solve complex problems

Flowchart

Diagram that represents an algorithm showing the steps as boxes of various kinds, and their order by connecting them with arrows.

3 basic programming constructs

Selection - Sequence - Iteration

3 elements of a successful algorithm

Accurate - Efficient - Consistent

Logical operators - AND

Two conditions must both be true for the whole statement to be true

Logical operators - OR

Either one of two conditions must be true for the whole statement to be true

Logical operators - NOT

Reverses the logic of a statement

Logic error

Error that results in incorrect or unexpected behaviour

Trace table

Used to identify logic errors in an algorithm or to determine the purpose of an algorithm

BIDMAS - order of calculations

BRACKETS - INDICES - DIVISION - MULTIPLICATION - ADDITION - SUBTRACTION

Iteration

Programming construct that allows the repetition of a process, also called a loop

Selection

Programming construct that allows a choice to be made between different options

Repetition

Repeating a block of code; for example a while loop which is controlled by a condition

Logic gate - NOT

"Accepts one input and produces one output. If the input is TRUE (1), the output will be FALSE (0). If the input is FALSE (0), the output will be TRUE (1)."

Logic gate - AND

"Accepts two inputs and produces one output. Both inputs must be TRUE (1) for the output to be TRUE (1) - otherwise, the output will be FALSE (0)."

Logic gate - OR

"Accepts two inputs and produces one output. At least one input must be TRUE (1) for the output to be TRUE (1) - otherwise, the output will be FALSE (0)."

Flowchart - selection symbol

Flowchart - process symbol

Flowchart - start / end symbol

Flowchart - input / output symbol

Truth table

Lists all possible combinations of input values to a logical expression and the corresponding output values.

Syntax error

A mistake in the program where the rules of the programming language are not followed.

Runtime error

Occurs while the program is running. A piece of code that contains an error causes the program to stop.

Sequence

Instructions are processed in order, one after the other