1. Using metric units of length
Lesson CCSS 4.MD.1
Literature Link: The Librarian Who Measured the Earth (story of Erastothenes) by Kathryn Lasky

2. Warm up
Kyle wants breakfast with juice and a piece of fruit. He can choose from pancakes, waffles, or cereal for breakfast. Kyle can choose apple juice, orange juice, or milk to drink. He can choose from an apple, a banana, or an orange. How many different breakfast combinations can Kyle choose from?

3. Think and write
What items would you measure using centimeters? List as many as you can think of.

4. Metric units of length
The metric units of length are used in many other countries as well as the USA. They are:
Millimeter (mm.)
Centimeter (cm.)
Decimeter (dm.)
Meter (m.)
Kilometer (km.)

5. Millimeters
Millimeters (mm.) are extremely tiny. There is no customary unit equivalent to millimeters.
One millimeter is equal to the thickness of a dime.
Millimeters are used to measure very small things like grains of rice or a tiny bug. Can you think of anything else you could use millimeters to measure?

6. centimeters
Centimeters (cm.) are larger than millimeters but smaller than inches. They are used to measure small objects.
A ladybug is about one centimeter long.
Can you think of some items you would measure using centimeters?

7. decimeters
One decimeter (dm.) is equal to 10 centimeters. It is another small unit of measure.
We do not commonly use decimeters in the United States, but the unit is used in other countries.
If 1 decimeter= 10 cm., then how many centimeters are in 5 decimeters?

8. meters
One meter is equal to 100 cm. Around the world, meters are used similarly to yards, though meters are smaller than yards.
What might you measure using meters? (Hint: Think of things you might measure with yards or feet.)

9. kilometers
Kilometers are the largest metric unit of length. One kilometer= 1,000 meters.
Kilometers are used similarly to miles, as they are often used to measure driving distances in other countries.
What could you measure with kilometers?

10. Practice!
Which unit is best to measure each item? Choose from mm, cm, dm, m, or km.
An ant’s leg
A bookbag
A newborn baby’s foot
A window
Distance from Germany to Spain

11. More practice!
10 cm or 10 m m or 3 km dm or 9 cm