Set the Stage to Engage in Math. This lesson is an inquiry based lesson working on the concept of missing addends. It includes a lock center, pages and instruction on how to "Set the Stage to Engage" this lesson.
I did not teach my students how to solve for the missing addend before this lesson.
All I said was that it was their job to figure what the missing number is.
I let them work in partners trying to solve the two problems on their own. Then, I included a center to let them practice this skill.