Pupils must learn to use the mathematical symbols + , – and = .
Expressions or equations involving these symbols should be introduced as a way to represent numerical situations and mathematical stories.
An expression such as 3 + 5 should not be interpreted as asking “What is 3 + 5 ?” but, rather, as a way to represent the additive structures discussed below, either within a real-life context or within an abstract numerical situation. It is important that pupils do not think of the equals symbol as meaning ‘and the answer is’.
They should instead understand that the expressions on each side of an equals symbol have the same value.
All examples used to teach this criterion should use quantities within 10, and be supported by manipulatives or images, to ensure that pupils are able to focus on the mathematical structures and to avoid the cognitive load of having to work out the solutions.
There are 4 additive structures (aggregation, partitioning, augmentation and reduction)
Pupils should learn to link expressions (for example, 5 + 2 and 6 – 2 ) to contexts before they learn to link equations (for example, 5 + 2 = and 6 – 2 = 4 ) to contexts.
For each case, pupils’ understanding should be built up in steps:
Pupils should first learn to describe the context using precise language (see the language focus box).
Pupils should then learn to write the associated expression or equation.
Pupils should then use precise language to describe what each number in the expression or equation represents.
Pupils must also be able to write and interpret expressions and equations to represent augmentation (increasing a quantity by adding more) and reduction (decreasing a quantity by taking some away). Note that ‘take away’ should only be used to describe the subtraction operation in reduction contexts.
“First 4 children were sitting on the bus.
Then 3 more children got on the bus.
Now 7 children are sitting on the bus.”
“We can write this as 4 plus 3 is equal to 7.”
“The 4 represents the number of children that were on the bus at the start.”
“The 3 represents the number of children that got on the bus.”
“The 7 represents the number of children that are on the bus now.”