Variables and data types

Lesson overview

Store values using clear variable names and choose suitable data types for each value.

Focus: Variables and data types.

What you will learn

• Explain a variable as a named storage location for a value.
• Choose suitable names for values used in a program.
• Recognise common data types including integer, real, Boolean, character and string.
• Explain why choosing the correct data type matters.

Before you start

• Input, processing and output.
• Basic arithmetic values.
• Everyday examples of names, scores and yes/no answers.

Variable choice scenarios

Use the score, username, temperature and logged-in examples to choose variable names and data types.

Variables and data types infographic

Explanation

A variable gives a value a name so the program can store it, change it and use it later. The name should make the meaning clear.

A data type describes the kind of value being stored. An integer is a whole number, a real number can include decimals, a Boolean is true or false, a character is one symbol, and a string is text made from characters.

Choosing a suitable data type helps prevent errors. A score can usually be an integer, a username should be a string, and a logged-in flag should be Boolean.

Worked examples

Quick checks

Practice

Exam practice ladder

• Fluency: recall the key term and use it accurately.
• Application: apply the idea to the scenario rather than giving a generic definition.
• Algorithmic reasoning: show the steps, condition or variable change clearly.
• Evaluation: explain why one method, structure or control is suitable.

Answers and marking guidance

Exact answers and marking guidance are hidden under each question. For this lesson, earn marks by naming the correct Computer Science idea, applying it to the scenario and showing the logic or value change clearly.

Common mistakes

• Using vague variable names when the meaning matters.
• Storing numbers as text when calculations are needed.
• Confusing a character with a string.
• Treating Boolean values as words instead of true or false states.

Extension

Design variables for a fitness tracker app: steps, distance, username and daily goal reached.

Next lesson

Next, continue with Operators and Expressions.

Exam-board guidance

Aplailasain is an independent learning resource and is not endorsed by any exam board.