1. Changing Units in the Customary System
Lesson 5-8

3. Strategy
When converting from a large unit to a small unit, multiply by the conversion factor.
When converting from a small unit to a larger unit, divide by the conversion factor.

4. Small Large
Inch (in) Foot (ft) Yard (yd) Mile (mi)
Ounce (oz) Pound (lb) Ton (t)
Fluid Ounce (fl. oz.) -- Cup (c) -- Pint (pt) -- Quart (qt) -- Gallon (gal)

5. Changing Units Determine the direction of the change (LS or SL)
Multiply or Divide by the appropriate conversion unit.

6. Changing Units of Length
Costume Design. Suppose you need 8 ½ feet of fabric to make a costume. Fabric is sold in yards. How many yards of fabric should you buy?
 divide because we are going from a smaller to a larger unit.
3 feet = 1 yard
8 ½ ft = 8 ½ ÷ 3

7. You Try:
Complete each statement.
45 in = ____ ft
in = ____ ft

8. Changing Units of Weight & Capacity:
Find the number of pounds in 28 ounces.
 divide because we are going from a smaller to a larger unit.
16 ounces = 1 pound
28 oz = (28 ÷ 16) lb

9. Continue: Find the number of quarts in 2 ½ gallons.
 multiply because we are going from a larger to a smaller unit.
4 quarts = 1 gallon
2 ½ gal = (2 ½ x 4) lb

10. You Try:
Complete each statement.
13 c = ____ pt
2 ¼ t = ____ lb

11. Computing with Units:
Growth. At age 12, Robert Wadlow was 6 feet 11 inches tall. At age 19, he was 8 feet 7 inches tall. How much did he grow from age 12 to 19?

12. You Try:
Your baby cousin was 6 pounds 8 ounces at birth. She gained 1 pound 9 ounces. How much does she weigh now?