Examples of what pupils should know and be able to do
Find the value of each of these expressions when a = 4:
3a² + 4 2a³
Find the value of y when x = –3:
Probing questions
When you substitute x = –1 into the formula y = 5x – 2 you get –7. Can you make up some more formulae that also give y = –7 when x = –1 is substituted?
When you substitute a = 2 and b = 7 into t = ab + 2a you get 18. Can you make up some more formulae that also give t = 18 when a = 2 and b = 7 are substituted?
p = 4a² and p = (4a)²
Are these two formulae the same or different?
When? Why?
What if pupils find this a barrier?
Adapt the classifying, matching, sequencing and pyramid activities from Teaching mental mathematics from Level 5 for use with simple formulae.
Give pupils completed exercises on substituting integers into formulae that include typical errors. Ask pupils to work in pairs to identify and explain the errors.
If necessary refer to guidance for simplifying and transforming linear expressions.
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