The second of these pages should probably be covered first; that is finding a pair of numbers that make 20. These types of question should follow on once children are confident and knowledgeable about finding pairs that make 10. These should be known. Progressing to finding pairs to make 20 should then be relatively simple.
If it is known that 4 + 6 make 10 then it is easy to work out what needs to be added to 14 to make 20.
Working out pairs that make 19 will often be done by ‘adding on’. For example;
What needs to be added to 7 to make 19?
Add 10 to 7 to make 17, then add two more by counting on to 19.
it can also be done by adding 2 to 7 to make 9 and then adding 10.
Don’t forget to ask your child what approach they took to reach the answer as both are equally valid.