Lesson 6.3 · Time and Measurement
Liquid volume
How much water fits in a fish tank? How much juice is in a jug? The amount of liquid a container holds is called its liquid volume. In this lesson you'll measure it in liters.
The liter
Definition
Liter
A liter is a unit for measuring liquid volume. We write it as L. So 3 liters is written 3 L.
To picture 1 liter, think of a large water bottle. Many big bottles of water hold about 1 liter.
| Container | About how much it holds |
|---|---|
| A drinking glass | less than 1 L |
| A large water bottle | 1 L |
| A bucket | 10 L |
| A bathtub | 150 L |
When you estimate, you make a smart guess. Compare the container to things you know. A bucket is much bigger than a water bottle, so it holds many liters.
Reading a measuring container
Some containers have marks on the side, like a ruler standing up. To read one, look at where the top of the liquid is. Then read the mark at that level.
Count the marks from the bottom: 1, 2, 3. The top of the water is at the 3rd mark, so there are 3 L of water.
Not every container counts by 1s. If the marks go 2, 4, 6, 8, count by 2s. Always check what each mark means before you read it.
Solving liquid volume problems
Liquid volume problems use the same math you already know:
- Add when liquid is poured together.
- Subtract when some is poured out or used, or to compare.
- Multiply when there are equal amounts in several containers.
- Divide when a total is poured equally into containers.
Always write the unit L in your answer.
Worked example: Estimate
Which is the best estimate for how much water a kitchen pot holds: 5 L or 500 L?
A pot is bigger than a water bottle, but much smaller than a bathtub (150 L). So 500 L is far too much. The best estimate is 5 L.
Worked example: Pouring together
A fish tank has 18 L of water. Jake pours in 7 L more. How much water is in the tank now?
Liquid is poured together, so add: . There are 25 L of water in the tank.
Worked example: Equal containers
A school has 4 jugs of lemonade. Each jug holds 3 L. How much lemonade is there in all?
There are 4 equal amounts of 3 L, so multiply: . There are 12 L of lemonade.
Worked example: Pouring equally
A farmer has 24 L of water. She pours the same amount into each of 6 troughs. How much water goes in each trough?
A total is shared equally, so divide: . Each trough gets 4 L.
Common mistake
A tall, thin container does not always hold more than a short, wide one. Height alone doesn't tell you the liquid volume. Pour both into the same measuring container to compare fairly.
Practice
Which is the best estimate for how much water a kitchen sink holds when it is full?
On this bucket, the marks count by 2s: 2 L, 4 L, 6 L, 8 L and 10 L from the bottom up. How many liters of water are in the bucket?
Type a number.
A cooler has 12 L of water. Ben adds 9 L more. How many liters are in the cooler now?
Type a number.
A kiddie pool holds 50 L of water. The kids splash out 18 L. How many liters are left in the pool?
Type a number.
Rosa buys 7 bottles of juice. Each bottle holds 3 L. How many liters of juice does she buy?
Type a number.
A worker pours 36 L of paint equally into 4 cans. How many liters go in each can?
Type a number.
Which one holds more than 1 liter?
Tom fills 5 buckets with 4 L of water each. Then he uses 6 L to water the plants. How many liters of water does he have left?
Type a number.