Your child is probably learning the Metric system at school, and many parents in the U.S. do not feel comfortable explaining the Metric system to their child, because it is not a system that they are very familiar with. The good news is, the Metric system is all a base-10 model. So, once you learn some basics, you will be converting between Metric units in no time (and so will your child!)

There are 3 basic types of measurement: Linear (length), Weight and Capacity. Today, we will be focusing on Capacity.

Prefixes in the Metric System

The following prefixes are used across all 3 types of Metric measurement:

**K**ilo-

**H**ecto-

**D**ek**a**–

BASE UNIT: meter (**m**)**, **liter** **(**L**)**, **gram (**g**)

**D**eci-

**C**enti-

**M**illi-

**Units of Metric Capacity**

**Kiloliter Hectoliter Dekaliter LITER Deciliter Centiliter Milliliter**

** **

**Even though there are a total of 7 prefixes, we commonly use **the milliliter (ml), centiliter (cl), and liter (L).

Converting Metric Units of Capacity

All the units in the metric system are either multiplied by 10 (when converting from a larger unit to a smaller unit) or divided by 10 (when converting from a smaller unit to a larger unit). For example, a kiloliter is a large unit, and if you wanted to convert it into liters, which is a smaller unit, you would have to multiply. Since the liter is 3 steps to the right from the kiloliter, you would multiply the number of kiloliters by 10, 3 times. For example, if you had 30 kiloliters, and you wanted to convert that into liters, you would multiply 30 x 10 x 10 x 10 = 30,000 liters.

If you memorize the order of the prefixes (see the hint below), all you need to know is that when you move one step to the RIGHT, you multiply by 10, and if you move one step to the LEFT, you divide by 10. Or, if you move 2 steps to the right, you would multiply by 10 x 10, 3 steps to the right would be 10 x 10 x 10, and so on.

Examples: 45 kiloliters = 45,000 liters

= 45,000,000 milliliters

34,000 milliliters = 34 liters

= 0.034 kiloliters

When your child first begins converting metric units, he will probably work with numbers that do not require him to go into the decimals, such as the last example above.

How to Remember the Order of the Prefixes

An easy way to remember the order of these prefixes is:

“**K**ing **H**enry **D**oesn’t **U**sually **D**rink **C**hocolate **M**ilk

Note: the “U” of “Usually” stands for “Unit”, as you can substitute meters, liters or grams here.

Try these:

67 liters = ______ milliliters

2,500 kiloliters = ________ liters

4,300 milliliters = ______ liters

12 kiloliters = __________ milliliters

*58 milliliters = _______ liters

Feel free to make up other conversion questions of your own!

WANT MORE?

- As always, playing math games at home is a great way to reinforce math skills learned in school.
- Have questions or ideas about this story?
- Need help or advice about your child’s learning?
- Have ideas for future Parent Homework Help stories?

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