Math Exercise: Comparisons

Select two boxes or cans of food that weigh 8 ounces and 16 ounces, respectively. Have students hold each as you tell them (or they read) the weights of the containers. Give students a box or can with the weight covered and have them compare the weight of the new package to the weight of the 8- and 16-ounce samples. Th ey can then estimate whether the new item’s weight is closer to 8 or 16 ounces. As students become more successful, they may want to predict a more specifi c weight. Ask them to tell you why they think the new can weighs 10 ounces, for example, and encourage them to respond with, “It is a little heavier than the 8-ounce can” or “It is much lighter than the 16-ounce can, but not as light as the 8-ounce can.”

With this estimation-promoting activity (which can easily become an independent activity), students also build number sense by experiencing the relationships between numbers and real measurements and by developing concepts of more than and less than.

To further develop these concepts, or for challenge work at the center, you can ask students how much they think an item costs. Th e goal is not for them to know prices, but to develop the concept that larger objects don’t necessarily weigh or cost more. If a student predicts that a $3 box of cereal costs $1 and you say “more,” he or she may say $2. You say “more” again, and the student will continue giving answers as you direct with “more” or “less” until the correct dollar amount is guessed. Continue this activity with a small can of a costly item, such as artichoke hearts.