This activity requires toothpicks and mini marshmallows. Place the students in groups of 3 (material manager, recorder, reader). Copy the 18 cards (I leave them on the full sheet and put them in a plastic paper protector - front and back), one set for each group. The groups are to answer the questions. When they have an answer to a question, the recorder can raise his/her hand. I can ask anyone in the group to answer the question. If it is correct, the group gets the number of toothpicks and marshmallows as given for that question (Building reward). 20 minutes to the end of the period, allow the students to use their marshmallows and toothpicks to build the tallest tower they can. The tallest tower wins. I recommend you have the tower built on wax paper to ease in cleanup.