"You have the peas ready. It must be math time."
This is two math activities in one. First you show them unshelled peas and ask them how many peas on the average are in each pea pod. Record their guesses.
Now open the pea pods and have them count how many peas are on each side, counting one side at a time and recording the numbers as an addition problem. (Number of peas on left side plus number of peas on the right side equals how many peas altogether.)
After you have done a few of these, have them figure out the average number of peas in pods by adding together all the answers to the equations and dividing by the number of equations you did.