Examples of what pupils should know and be able to do
Probing questions
Can you explain to me an efficient method for adding 19?
Why is this a good mental method for adding 19? What is the difference between adding 19 and subtracting 19 using this method? Show me why this is, using a 1-100 grid.
What if pupils find this a barrier?
Number Grid ITP - Zip file (462Kb) may be useful in establishing quick ways to add, for example, 29 i.e. add 30 and then subtract 1.
Counting on and back ITP - Zip file (456Kb).
Use bead strings that are grouped in tens to practise adding and subtracting near multiples of 10.
Encourage pupils to see equivalent calculations e.g.
26 + 19 will have the same value as 25 + 20;
52 − 19 will have the same value as 53 − 20.
Teaching mental calculation strategies to level 5 booklet DfES 0744-2004G from QCA
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