This activity is a great follow-up activity to a lesson on the subtraction strategies of counting up and counting back to find the difference. The students build a brick wall by solving various subtraction problems using either the counting up or counting back strategy. Once the students have solved the subtraction problems on the various bricks, they cut them out and paste them on the correct side of the wall ... the counting up side or the counting back side. A great activity that helps students to think about the most efficient strategy to solving various subtraction strategies. This activity meets or exceeds the Common Core Standards of Mathematics and makes for a great whole class activity or math center.