Here's a page for use with the book THE GREEDY TRIANGLE by Marilyn Burns. As the triangle changes its shape, students build each shape with marshmallows and toothpicks and record information about sides, angles, and vertices.

Here's a SMARTBoard lesson to accompany the book Ten Flashing Fireflies SMART board lesson has been made to accompany the book TEN FLASHING FIREFLIES by Philemon Sturges.