Students should choose one of the flat patterns from activity C and make a copy of it on the large two-inch grid paper. Students then must add the least number of flaps need to be able to fold the pattern and glue it together to make a box with a lid that opens. The lid should have one flap that tucks in to close the box. Students should label each flap drawn to be glued or be part of the lid. Students then cut out their patterns and glue them to see if they work.

Extension questions for class discussion or to be answered in a math journal: What did you have to think about wile you were making your pattern? Is there a rule for the number of flaps a box requires? Does the box below work? Explain why or why not.