Measure Length to the Nearest Unit

What you'll learn

Estimate and measure length using inches and centimeters
Choose an appropriate tool and unit for a measurement
Compare the lengths of two objects

Words to know

Length —: how long something is
Inch —: a U.S. Customary unit of length
Centimeter —: a metric unit of length
Ruler —: a tool used to measure length
Estimate —: a good guess about how long something is

Why it matters Measuring length helps us build, sort, and compare things, like seeing which pencil is longer or how tall a plant grew.

Worked examples

Model ItI do

How do you measure a crayon with a ruler in inches?

Line the end of the crayon up with the 0 mark on the ruler. Read the number at the other end. If the crayon ends at the 4 mark, it is about 4 inches long.

Try It TogetherWe do

Would you measure the length of your classroom in inches or feet?

A classroom is large, so feet is the better unit. Inches would give a very big number and take a long time to measure.

Now YouYou do

Would you use a ruler or a measuring tape to measure the length of a playground?

Think about which tool fits a long distance. Check your answer in the back of this chapter.

Practice

Mastered 0 of 11

Warm-up

Ease in with the basics.

1.Which is longer: your foot or a whole bus?
2.What tool do you use to measure how long a pencil is?
3.Which unit is smaller: a centimeter or a meter?

On Level

The core Quick Check from the book.

1.Which unit is smaller: an inch or a foot?
2.Which tool would you use to measure a book: a ruler or a scale?
3.About how long is a new pencil: 7 inches or 7 feet?
4.A ribbon is 5 inches and a straw is 8 inches. Which is longer?
5.Which unit is metric: inch or centimeter?

Challenge

Stretch your thinking.

1.A crayon starts at the 0 mark and ends at the 3 mark on an inch ruler. How long is it?
2.One string is 9 centimeters and another is 6 centimeters. How much longer is the first string?
3.Would you measure the length of your desk in inches or in miles?