Children can act out word problems. They must count out the amounts and add or subtract to see if the operation is possible. Have students write their own math problems for each other or another class. To make them more challenging, set parameters like they have to include 2 operations or subtraction with regrouping. Have them write the math problem, story solution, and draw a model to show it.
Third grade has a geo adventure that s good for map reading review.
Have them explain concepts in writing. This is a great assessment to see if they really understand something. My kids keep a thinking log. Play games where you are giving clues to identify numbers. Use these to break numbers apart for kids.