Polly's new pen-pal, Ally, lives in Montreal, Canada, where they use the metric system. Polly and Ally have lots in common: They both have cats, like the color purple, and are just about the same size and weight. But when Ally writes that she is 125 centimeters tall, Polly needs to ask her Dad for help to figure out how tall that really is. Dad uses a baseball bat about 1 meter—100 centimeters—long as a reference, and shows Polly that one centimeter is about the width of his little finger. Dad helps Polly figure out grams and kilograms, and meters and kilometers, also by using every day references she can relate to.
The use of rough equivalents in terms of familiar objects and distances helps kids become familiar and comfortable with the metric system.
Illustrated by Rémy Simard.
A large grapefruit is the rough equivalent of a kilogram. Have your child (or students) take turns holding a grapefruit, feeling its weight. Then have them pick up other objects such as a book, a bag of candy or Mom's purse and decide whether each object weighs more or less than a kilogram.
Have your child (or students) lie down on butcher paper or newspaper. Trace around their bodies with a marker. Measure, in centimeters, height and the length of an arm, leg and little finger.
Cut several strings into 10-centimeter lengths. Give your students the strings and ask them to find objects that measure about 10 centimeters. The first child to find five objects is the winner.