1 Great Groupings. Collect a variety of bottle caps that vary in size, color, and texture. Invite a few children to sort the caps into like groups. Notice the different ways that children sort and classify caps. They may sort by size, shape, or color, or separate the plastic caps from the metal caps. Once they have completed their sorting, encourage them to describe their choice of groupings.

2 Size Them Up. Give each child a variety of bottle caps that vary in size. Invite them to organize the caps from smallest to largest. Then ask them to reverse the order and arrange them from largest to smallest.

3 What's Their Weight? Provide children with a pan scale and a variety of bottle caps. Invite them to compare the weight of plastic and metal bottle caps. Which weighs more? Ask them to place a large bottle cap on one side of the scale. How many small caps are equal to the weight of the large cap? Are three large caps equal to the weight of three small caps?

4 Fill 'N' Count. Fill a small clear plastic container with bottle caps. Invite the children to estimate how many bottle caps are in the container and record each child's estimate. Now ask them to count the number of bottle caps and compare their predictions. Then, give them another container, either smaller or larger, and ask them to estimate how many small bottle caps will fill the container. Invite children to count the caps as they fill it up.

5 Perfect Pairs. Collect enough bottle caps to have one pair of each. Mix them up and place them in a pile on the table. Give children time to explore the different bottle caps. Then invite one or two children to find the matching bottle caps. How many pairs of bottle caps did they find? What makes them similar/different from the other caps?