First we review a system that students are very familiar with: time. We apply students’ understanding of time with word problems and record measurement equivalents in a two-column table.
Students next work with metric measurements. They learn that word parts help us understand what metric units mean:
centi- means one hundredth (1/100)
kilo- means 1,000
milli- means one thousandth (1/1000)
So a centimeter means 1/100 of a meter, a kilogram means 1,000 grams, a kilometer means 1,000 meters, a milliliter means 1/1,000 of a liter, and a millimeter means 1/1,000 of a meter.
Students also use physical objects, including meter sticks, rulers, scales, weights, and cylinders to make these units meaningful. These objects help them answer the following kinds of questions:
What metric unit would you use to measure an ant?
Would meters or kilometers be a better way to measure the distance from school to your house?
What could you measure with milligrams?
Do you think a full soda bottle holds 2 liters or 2 milliliters of soda?
Finally, students gather objects from home and the classroom to measure. They must first estimate and then check their estimates with a measuring device (scales, rulers, meter sticks, cylinders).
After students are comfortable with metric units, we repeat the process for standard units:
pounds and ounces
yards, feet, and inches
fluid ounces, cups, pints, quarts, gallons