Students will be expected to understand and use the following Boolean…

The idea

Understanding means knowing what each operator does to its inputs and outputs; using means applying them in expressions and truth tables. NOT is unary and inverts one value. AND is binary and gives 1 only when both inputs are 1. OR gives 1 when at least one input is 1. XOR gives 1 when the inputs differ. Recognise each operator's symbol and name, then apply it correctly when building or evaluating an expression.

For example: With A = 1 and B = 0, A AND B = 0, A OR B = 1, A XOR B = 1 and NOT A = 0.

What earns the marks

• NOT is a unary operator that inverts a single Boolean value.
• AND is a binary operator that outputs 1 only when both inputs are 1.
• OR is a binary operator that outputs 1 when at least one input is 1.
• XOR is a binary operator that outputs 1 when the two inputs differ.
• Each operator can be applied to given input values to produce a correct output.
• Operators can be combined in expressions and checked with a truth table.

Common mistakes and how to put them right

• Confusing the behaviour of OR and XOR.

  Put it right: XOR gives 0 when both inputs are 1, while OR gives 1.

• Treating NOT as a binary operator.

  Put it right: NOT applies to a single value.

• Mixing up which operator needs all inputs to be 1.

  Put it right: AND requires every input to be 1.

Exam tips

• Learn each operator's output rule so you can state results quickly for given inputs.
• Practise applying operators to two-input combinations to build confidence with truth tables.
• Check whether an operator is unary or binary before applying it.