Have you ever tried to make sense of liters and milliliters? Well, these metric units of capacity are also found in the metric playground. Remember the metric playground from the Equivalent Metric Units of Mass Concept? Sam and Olivia have figured out the mass dilemma and have now moved on to a problem about capacity.

The two move on to a birdbath. Together, they need to fill one 4.5 liter birdbath with water using a scoop. Once they have it filled, the sign above the birdbath will light up and tell them how many milliliters are in 4.5 liters. “I think I can figure this out without filling the birdbath,” Olivia says.

Can you figure it out? How many milliliters can be found in that 4.5 liter birdbath?

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Think about this question as you work with metric units of capacity in this Concept.
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### Guidance

When we think about
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capacity
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, often referred to as volume, we think about measuring liquids. In the Metric System of measurement, we measure capacity using two different measures, liters and milliliters.

Since there are only two common metric units for measuring capacity, this text box shows them and their equivalent measures. Liters are larger than milliliters. Notice that prefix “milli” again.

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When converting from large units to small units, you multiply.
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When converting from small units to large units, you divide.
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4 liters = _____ milliliters

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Liters are larger than milliliters, so we multiply by 1000.
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4 liters = 4000 milliliters

Use what you have learned to write each equivalent unit of capacity.

#### Example A

5 liters = _____ milliliters

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Solution: 5000 milliliters
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#### Example B

2000 milliliters = _____ liters

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Solution: 2 liters
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#### Example C

4500 milliliters = _____ liters

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Solution: 4.5 liters
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Now let's think about Sam and Olivia and a birdbath. Here is the information that we already know.

The birdbath holds 4.5 liters of water.

Now that you know that there are 1000 milliliters in one liter, you can figure out how many milliliters will fill the birdbath by multiplying 4.5 1000.

We move the decimal point three places to the right when we multiply by 1000.

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Our answer is 4500 milliliters.
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Wow! You can see why it makes much more sense to measure the amount of water in the birdbath in liters verses milliliters.
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### Vocabulary

- Customary System
- The system of measurement common in the United States, uses feet, inches, pounds, cups, gallons, etc.

- Capacity
- the amount of liquid an object or item can hold

### Guided Practice

Here is one for you to try on your own.

Jamie is transferring liquid from one container into a larger container. She transfers 2.5 liters. How many milliliters did she transfer?

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Answer
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We know from the Concept that there is 1000 milliliters in 1 liter. Therefore, Jamie transferred 2500 milliliters of liquid.

### Video Review

Khan Academy Conversion Between Metric Units

James Sousa Metric Unit Conversions

### Practice

Directions: Convert to an equivalent unit for each given unit of capacity.

1. 4500 mL = ______ L

2. 6900 mL = ______ L

3. 4400 mL = ______ L

4. 5200 mL = ______ L

5. 1200 mL = ______ L

6. 1800 mL = ______ L

7. 2900 mL = ______ L

8. 1300 mL = ______ L

9. 2700 mL = ______ L

10. 3 L = ______ mL

11. 5.5 L = ______ mL

12. 8 L = ______ mL

13. 9.3 L = ______ mL

14. 34.5 L = ______ mL

15. 65.5 L = ______ mL