Here is a page for checking understanding of halving. The numbers to halve are all multiples of 10 so it is important that children are confident with halving numbers up to 20 before trying this. By Year 3 children should be knowing these halves off by heart.
The questions with a whole ten answer are very straightforward. The tricky bit is halving a number such as 70. Probably the best approach to begin with is to split the 70 into 60 and 10. Halve the 60 (that’s 30) and halve the 10 (that’s 5) and add the 30 and 5 to make 35.
After a while this will become second nature as the process is mentally ‘internalised’.
This can be found in our Year 3 Calculating category.