This book can be used for intervention or with a whole class when the strategy for adding or subtracting 1, 2 or 3 is introduced as counting on and counting back.

I have seen many children over the years who have not mastered this simple level of mental computation. Most of the time it was because they did not have a strategy they could rely on before the facts became fluent. They did not recognise adding or subtracting 1, 2 or 3 could be done mentally by counting on or counting back.

Over time I realised it was difficult for them to recognise the facts that fell into the COUNT ON and COUNT BACK category, so I started there. Too many used a counting strategy, using their fingers, for all number facts, but especially addition. This is not as effective strategy once the numbers stretch beyond three. 

Once students recognise COUNT ONS and COUNT BACKS, the next skill deficit I saw was a skill deficit in counting forwards or backwards from a given number (starting from the given number) instead of the next number. You will recognise this deficit when answers are 1 number out. I have used numbers on a number line to support those students.