Ask students to pour the peas onto the tray so they can see all the peas at
once. Each group should look for ways the peas are similar or different.
4. Tell each group to choose three differences (variables) including one
that can be measured with the ruler.
5. Monitor the class as they decide which characteristics of peas they will
select. Those who can't find any characteristics other than color, texture,
or size might need a little prodding. Ask those students a question such
as, "What other differences do you see?