-Play the same activity with rectangles. Emphasize that rectangles have four straight sides and are closed figures. Talk about squares being special rectangles that have four equal sides.
"Read the story "The Greedy Triangle" by Marilyn Burns. In this story a triangle is tired of having just three sides so he asks the "shapeshifter" for four sides. Bored with four sides, he asks for five and so on. Have fun with your child learning the name of various shapes all the way up to a dodecagon, or twelve-sided shape.
Adjust for an older child
After the activity, have the child make a book of examples and non-examples of triangles.
Adjust for a younger child
Most young children think of a triangle as having three equal sides. Show them several examples of triangles before playing the game.