By the end of year 2 (children aged between 6 and 7) children are expected to know doubles of all numbers up to 20 and to be able to quickly derive halves. This is quite a tall order, so plenty of practice and repetition is needed. The first of these pages gives you examples of the type of questions to ask and there is still a place for using apparatus (coins, counters etc) to double or half amounts. The second is an example of doubling numbers in the teens. Don’t go onto these until your child is very confident and knowledgeable about doubling single figures.
Some numbers are easy to double and to learn eg 5. Numbers above 5 are harder as they give answers in the teens. It also helps to know what odd and even mean. Keep halving to even numbers at this stage, although in the real world they will soon come into contact with halving odd numbers.