3rd Grade - Write How To Convert Units

Write How to Convert Units
Express simple unit conversions in symbolic form (e.g., __ inches = __ feet x 12).
Algebra and Functions: unit conversions (inches, feet, etc.) The ability to convert simple types of measurement within a system of measurement (U.S.).

Sample Problems


Volume: 1 gallon = 4 quarts; 1 quart = 2 pints; 1 pint = 2 cups


The abbreviation for gallon is gal. The abbreviation for quart is qt. The abbreviation for pint is pts. The abbreviation for cup is c.


Weight/Mass: There are various systems of weights around the world. We use:

1 ounce = 16 drams; 1 pound (lb.) = 16 ounces (oz.); 1 ton (tn.) = 2000 pounds.


Length: 1 foot (ft.)= 12 inches (in.); 3 feet = 1 yard


Time: 1 hour = 60 minutes; 1 minute = 60 seconds; 1 hour = ? seconds (3,600)

Learning Tips


Children can explore measurement in nonstandard forms by using their feet and hands. They can measure household objects.


From the Columbia Encyclopedia: Long distances by land or sea were measured by the day’s journey. “Ten-Sleep Lake,” named by Native Americans, measured maybe its length, or the distance around it.

The size of a field that a man with a yoke of oxen could plow in one day was a furrow-long (furlong), and its width that of four yoked oxen abreast, or 1 rod (about 16 ft.).

1 pace was 3 ft., 1 mile was 1000 paces.

Four oxen in their stalls were allowed 16 ft. of stall space. 16 ft. is still a standard length of boards.

The ft. was the length of a man’s foot. The hand was the width of a man’s hand (4 inches).

The yard was the length of a step, or the distance from the nose to the finger-tips.

The fathom was from finger-tips to finger-tips of the outstretched arms (6ft.).

The inch was the outer joint of the thumb, or the length of 3 grains of barley placed end to end.


After talking about measurement in a practical way, children can be asked what other things can be measured besides lengths? (liquids, weights, time).


Try to relate each type of measurement to children in a practical way, using everyday objects that they are familiar with. For example, children can carefully measure 1 cup of water and pour the entire cup into a tall glass. They can use the same cup to measure out another cup of water and pour that one into a bowl, vase, or another container of a size and shape different from the original glass. Children can measure that the water doesn't come up to the same height in all of these containers. Help them to figure out that the diameter of the container influences the height of the liquid in a container. (Children under 6 often cannot reconcile these differences; don't worry about it if younger children are present.)

Water can then be measured using various sizes of measuring device. Fill a gallon jug with water and pour the water into 4-quart containers. Pour the water from one quart into 2 pint bottles. Pour one pint into 2 cups. Finally, allow children to estimate how much water it will take to fill a one-cup measure by encouraging them to pour water into a container that you know holds more than one cup and then remove water until they believe that what is in the container is a cup of water. Test the assumption by pouring it into the standard measuring cup. (Teach children that you must hold the measuring line that you need on cup up to eye level or the measurement isn't accurate; they can test this themselves by holding the cup higher or lower.)


Allow the child to be a timekeeper around the house. They are responsible for keeping track of cooking times for food, times to leave the house and times to go to bed. Children can determine how many minutes they slept if they know how many hours they slept. If a casserole needed to be in the oven for an hour and 15 minutes, for example, what is the total number of minutes it needed to bake?

Children enjoy being "timed" for many activities. How long does it take to walk to the corner? How long does it take to put away the toys?

You might also ask your child to tell you when 1 minute has gone by while you watch the second-hand of a clock.

Extra Help Problems


1 gallon = ? cups (16 cups)


1 gallon = ? pints (8 pints)


1 quart = ? cups (4 cups)


3 gallons of milk = ? cups (48 cups)


2 ½ gallons of juice = ? quarts, ? pints, ? cups (10 quarts, 20 pints, 40 cups)


½ gallon of soya = ? quarts (2 quarts)


5 gallons of lemonade = ? cups (80 cups)


2 ounces = ? drams (32 drams)


2 pounds = ? ounces (32 ounces)


1 ton = ? ounces (32,000 ounces)


4 tons = ? pounds (8,000 pounds)


2 yards = ? inches (72)


6 inches = ? foot (1/2)


2 feet = ? inches x ? (12 x 2 = 24 inches)


3 yards = ? inches x (36 x 3 = 108 inches)


1 foot = 2 yards - ? feet (2)


1 hour + 30 minutes = ? hours (1.5)


60 seconds + a half a minute = ? seconds (90)


½ second + ½ second + 59 seconds = ? (1 minute)


5 minutes – 2 minutes = ? seconds (180)


5 yards = ? feet, ? inches (15 feet, 180 inches)


The carpenter asks you to measure a 2 x 4 wooden plank that’s big enough to fit across a 3-foot ditch. How many inches do you have to measure? (36 inches)


If Cindy had 15 inches of string candy and Mike had 15 more, how many more do they need before they have a yard? (6 inches more)


Your mom asks you to pour 2 pints of water into the soup, but you only have a measuring cup. How many cups will you pour in? (4 cups)


You need 100 gallons of water for a dunk tank in your backyard. How many quarts would that be? (400) pints? (800) cups? (1600)


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