My students have been using a variety of addition and subtraction strategies to help them solve math equations. As is typical for this time of year, they are stronger with addition concepts. We have been working with a lot of addition equations with missing addends to help them discover the relationship between addition and subtraction.
here for a free copy. All students need is a die and a crayon or marker. You many use 1 or 2 colors.
Here is another one.