Free maths worksheet from mathsblog.co.uk
Here is a page with a difference for year 3 children. All the numbers, both questions and answers are supplied, but the signs are missing. Just pop the signs in to make the number sentences correct.
This will show whether a child has a good sense of number for the four rules. It might well not be necessary to work out the answer, just eliminate possibilities.
Use a calculator to check whether the correct signs have been inserted.