This activity shows that math helps us “shop smart” and save money:

1. Before a shopping trip, talk with your child about how to compare prices. Explain that you need a common measurement to use, such as ounces or inches.

2. Make a shopping list and decide to find the best value for several items. Bring a pencil and paper to the store.

3. Find the first item and notice how it is measured. For example, juice is usually measured in ounces. One jug might cost $1.89 for 64 ounces, while another might cost $0.98 for 32 ounces. Assuming the two kinds of juice taste similar, which is the better buy?

4. Help your child solve the problem like this: Divide the cost by the number of ounces. The brand with the smallest answer is a better deal. (In this example, it’s the 64-ounce jug.) Can she find the best value for other things on your list?

5. Once your child has the hang of it, give her some new challenges. Can she compare prices using metric measurements? Can she compare items that are priced differently, such as apples that are $2.00 a pound and oranges that are six for $0.99? (Hint: This requires weighing each product.)

If your child enjoys this activity, she can practice by using store ads. She might also factor in the worth of coupons.

Here’s another idea: Graph prices over time. Are certain brands always less expensive? When prices change, can she guess why?

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