To find out if your child has retained something – e.g. dividing fractions, ask them to write up a question on the whiteboard to test YOU
The reason this works is because the child has to think of a realistic question to ask, e.g. 2/5 ÷ 1/3 (rather than 234/432 ÷ 99/17 which would take a while longer to solve).
In addition and most importantly, the child has to be able to answer their own question – to mark you as having succeeded or failed in answering the question.
Experience has shown that this method works for most aspects of Key Stages One and Two including geometry and charts etc.
A side-benefit of this approach is that it’s a lot of fun.
What if the child gets their own question wrong?
That’s ok, you simply point out where they went wrong, and you go again.