The student responded by drawing these figures, and providing this explanation on how to make the rectangle:

"I folded the top down and cut along the fold. Then I turned the cut piece and moved it to make a rectangle."

• If this were your student, could you determine whether he understood why the figure he produced was a rectangle?
• To what extent has the student shown what he knows about the properties of triangles and rectangles?
• Is this reasoning clear?

Try this problem yourself, to help you determine the reasoning involved.

  Look at a related problem