What You Need
- Bathroom or kitchen scales
- Objects to weigh, such bags of sugar, flour, potatoes or onions; boxes of detergent and cookies; shoes of different sizes
- Paper and pencil
- A small plastic zipper bag filled with sugar and much larger zipper bag filled with cornflakes (or popped popcorn)
What to Do
Show your child two objects, such as a five-pound bag of sugar and a ten-pound bag of potatoes and ask him to guess which weighs the most. Show him how to use a scale to weigh the objects and see if his guess is right or wrong.
Next show him several objects and ask him to guess how much each weighs. Have him write his estimates, then weigh the objects to see if they're correct.
If you choose, have your child estimate his own weight, as well as that of other family members, and use the bathroom scale to check his guesses.
Extend the activity or make it more challenging by doing the following:
- Show your child the small plastic bag filled with sugar and the larger bag filled with cornflakes or popped popcorn. Ask your child, which will weigh more, the smaller or the larger bag? Have him weigh the bags to check whether his guess is correct. Afterwards, point out that bigger does not always mean heavier.
- Ask your child how he can weigh a suitcase that is too large to fit on the bathroom scale. Listen carefully to his answers-try some of his suggestions, if possible-and praise him for learning to think through problems. If he doesn't come up with a solution, show him that one way to find the weight of the suitcase is for him to stand on the scales while holding it and noting the total weight. Then put the suitcase aside and weigh himself again and note his weight. If he subtracts his weight from the total weight, the answer is the weight of the suitcase.
Source: U.S. Department of Education, Office of Communications and Outreach, "Helping Your Child Learn Mathematics," Washington, D.C., 2005
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