Measuring Length
Lessons in this chapter
About Measuring Length
How long it is replaces 1st grade’s paperclips with real units, and introduces both measurement systems rather than choosing one.
Measure Length using Centimeters comes first because the centimeter is small enough to see and big enough to count. The practical rule kids need is to line the object up with zero rather than the end of the ruler, which is the same fair-start idea from kindergarten.
Measure Length using Meters and Millimeters and Measure Length in Inches, Feet and Yards cover both systems. Metric units relate by tens, which makes converting easy. Customary units do not: twelve inches to a foot and three feet to a yard have to be learned, and that contrast is worth naming out loud.
Measure Length using Mixed Units of Measurement handles the awkward real case, 1 m 25 cm, where a measurement uses two units at once. Solve Applied Problems on Comparison and Addition and Subtraction of Length then puts the arithmetic to work, with the rule that only like units can be added.
Measure Length using Centimeters, Measure Length in Inches, Feet and Yards and Solve Applied Problems on Comparison and Addition and Subtraction of Length each come with a worksheet worked in the page and marked as you go. Metric and customary units get separate lessons, which is what lets the mixed-unit lesson in between them work. All five are free.
Frequently asked questions
Measuring in centimeters, then in meters and millimeters, then in inches, feet and yards, then in mixed units, and finally applied problems on comparing, adding and subtracting lengths. Both measurement systems are covered because a 2nd grader in the US will meet both. It sits in Measurement and Data (2.MD).
Millimeters, centimeters and meters in the metric system, and inches, feet and yards in the customary one, plus measurements that mix two units.
Starting at the end of the ruler rather than at the zero mark. Most rulers have a small margin before zero, and every measurement comes out long if it is ignored.
Because both are in daily use. The contrast is also useful: metric units convert by tens, customary ones do not, which shows why the metric system is easier to calculate with.
Twelve, and three feet make a yard. Unlike metric conversions these have to be memorized, since there is no pattern to work them out from.
Giving a measurement with two units, like 1 m 25 cm. It is how people actually state heights and distances, so kids need to read and write it.