Before you complete the worksheets play ping pong with an adult or family member.
Start with number bonds to 10, then progress to 20 if you are able. First take it in turn to say 'ping', then the other person says 'pong'. Now the first person says a number e.g. '8', then the child has to work out how many more to make 10 e.g. '2'. Repeat with other numbers. How fast can you do this?
You could use fingers, pieces of pasta or coins to support your child if needed.