Straws and pipe cleaners are terrific materials for building models of pyramids and cubes. Start out building a triangle or square, then make it three dimensional and turn them into pyramids or cubes by adding more straws. Try making two triangles into a square! This activity is a great introduction into geometry and measurement. The activity does not go into detail about how to use the pipe-cleaners with the straws, but taking non-bendy regular drinking straws and filling them with pipe cleaners so that a little sticks out on either end, works best. The straw keeps the structure sturdy, and the pipe cleaner ends are used to twist tie other pipe cleaner/straw combos together.