AQA · GCSE · Computer Science
Course version: 8525 · Version from Sept 2020
Students will be expected to understand and use the following logic…
Full specification wording
Boolean logic: Students will be expected to understand and use the following logic circuit symbols:
This criterion asks you to recognise the standard symbols for logic gates and to use them when reading or drawing circuits.
Checked against the AQA 8525 specification (opens in a new tab) on .
- Point 9 of 16
Study notes
From the checked teaching notes for this specification point.
The idea
This criterion asks you to recognise the standard symbols for logic gates and to use them when reading or drawing circuits. For each gate, learn the distinctive shape: NOT is a triangle with a small circle at its output; AND has a flat back and rounded front; OR has a curved back and pointed front; XOR resembles OR but has an extra curved line at the input side. Match the shape to its function: NOT inverts a single input; AND outputs 1 only when both inputs are 1; OR outputs 1 when at least one input is 1; XOR outputs 1 when the inputs differ. In a multiple-choice question you may be shown a symbol and asked to name it, or given a name and asked to pick the matching symbol, so practise both directions and check the small circle on NOT carefully.
What earns the marks
- NOT is drawn as a triangle with a small circle at the output and inverts its single input.
- AND has a flat back and rounded front and outputs 1 only when both inputs are 1.
- OR has a curved back and pointed front and outputs 1 when at least one input is 1.
- XOR resembles OR but carries an extra curved line at the input side and outputs 1 when the inputs differ.
- Recognising a symbol and naming its gate is the same skill as choosing the correct symbol for a named gate.
Common mistakes and how to put them right
Mixing up OR and XOR symbols.
Put it right: XOR has an additional curved line at the input side that OR lacks.
Forgetting the small circle on the NOT symbol.
Put it right: The circle marks inversion, so a triangle without it is not NOT.
Confusing AND and OR shapes.
Put it right: AND has a flat back with a rounded front, while OR has a curved back and a pointed front.
Assuming the symbol set differs by tier.
Put it right: The same symbols apply to foundation and higher.
Exam tips
- Learn each symbol in both directions: symbol to name, and name to symbol.
- Check the input side of a curved gate to decide whether it is OR or XOR.
- Look for the small output circle to confirm a gate is NOT before choosing an answer.
Try the lesson
The start of the Boolean logic: Students will be expected to understand and use the following logic circuit symbols: lesson, made from checked teaching notes for this specification point.
Have a go first
A logic gate symbol is drawn as a D-shape with a flat straight edge on the left and a curved edge on the right, with no small circle on its output. Which gate does this symbol represent?
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