Give students this printable and a bowl of round cereal or round candies. Fruit Loops, Cheerios, or M&Ms work well. Have students estimate how many cereal rounds or candies will fit into each graphic. Then have students glue or place the cereal or candies in the graphics until they are full. Instruct students to count the cereal or candies to check their estimate.
This activity is inspired by a The Mailbox estimation worksheet from 2009.