During the preparation stage of the game, there is no competition. Each students should receive an equal amount of marshmallows and toothpicks. The teacher shows them how to make various, two-dimensional shapes with their supplies. They begin with the triangle, then the square, followed by the pentagon and so on. Each shape should be repeatedly identified and copied on the board ahead of time. As a reward for correctly making each shape, a student can each eat a marshmallow.
At this point a little competition begins, but without keeping track of points. The teacher asks kids to review their triangles before asking them to make a three-dimensional shape out of them. If no one comes up with a solution, the teacher can show them how to make a tetrahedron with three more toothpicks and a another marshmallow. With this example in front of everyone, the teacher now asks them to make as many three-dimensional shapes as possible from the square.
The teacher puts the students into teams, using results from the earlier activities to balance membership between advanced students and those who are struggling. The instructions are to create a large structure out of multiple three-dimensional shapes using toothpicks. The teacher can set a height requirement and a time limit depending on the resources and the capabilities of the classroom, and then award extra marshmallow treats for the team that wins.
Along with a height requirement, the teacher allows a maximum number of toothpicks and marshmallows. Teams will have to think carefully about how to create a shape that will reach maximum height with a limited amount of materials. The teacher can prompt them to look at previous constructions and ask about apparent strength. Ideally, kids will grasp that the triangle is the strongest elementary shape.
Teachers can invite kids to make any shape they want, so they can blow off steam. To keep the resulting activity marginally educational, the teacher can require that all shapes contain recognizable geometry.