This lesson teaches them to build the formula for surface area themselves. After tracing the faces of a rectangular prism, students are prompted to construct the areas of each face into one comprehensive formula. They then repeat this process for a triangular, parallelepiped and trapezoidal prism, as we as 2 challenge problems.
Please note, this is dependent on having a class set of these prisms for students to handle during the lesson.
This is one of 12 lessons in my "In and Out" unit that targets area and volume for 7th graders in the advanced track. The goal of the unit is to build understanding of why the formulas for area and volume work, such that if students forget the formulas, they can cognitively reconstruct them on their own.