Grade by Grade
E. Spatial Sense · 3D Objects, Directions and Measurement

Capacity: How Much Does It Hold?

E2.3 E2.5About 35 minutes
Learning goals
  • I can explain what capacity means.
  • I can estimate, measure and compare capacity using non-standard units like cups and scoops.
  • I can explain why overfilling, underfilling and gaps make a measurement wrong.
  • I can explain why a smaller unit gives a bigger count, even though the capacity stays the same.

Words to know

capacity
How much a container can hold.
container
Something that holds things, like a cup, a pot, a jar or a box.
non-standard unit
A unit that is not an official unit, like a scoop, a cup or a yogurt container. It must be the same every time you use it.
overfill
Put in more than the unit holds, like a heaped scoop.
underfill
Put in less than the unit holds, like a half-full cup.
level
Filled exactly to the top, with nothing piled above.

Let's start in the kitchen

You're making soup with a grown-up. You want to fill the big pot with water, but you only have a small cup. How many cups of water will the pot hold?

The amount a container can hold is called its capacity. A pot has a bigger capacity than a cup.

A large steel cooking pot, a small white cup of water and a glass pitcher of water on a kitchen counter.
The big pot has a much greater capacity than the small cup. How many cups of water do you estimate it would take to fill the pot? AI-generated image

Measuring capacity with units

To measure capacity, pick a unit: a small cup, a scoop, or a yogurt container. Then:

  1. Estimate first: "I think the pot holds about 10 cups."
  2. Fill the unit level, right to the top.
  3. Pour it into the container. Count 1.
  4. Keep going until the container is full. Count each one.
  5. Say the number and the unit: "The pot holds 12 cups."

You can measure with water, sand, rice or dried beans. They all pour and fill every space.

1 cup×6jar holds 6 cupsFill to the topand count
A cup is the unit. The jar holds 6 level cups of water.
Worked example

Example 1: Compare two containers

Using the same scoop, a mixing bowl holds 9 scoops of rice and a pot holds 14 scoops. Which holds more? How many more scoops?

  1. Both were measured with the same scoop, so we can compare the numbers.
  2. 14 is more than 9, so the pot holds more.
  3. 14 − 9 = 5.

The pot holds 5 more scoops than the bowl.

Being accurate: overfilling and underfilling

Every scoop must hold the same amount. If it doesn't, your count will be wrong.

leveljust rightheapedtoo muchnot fulltoo little
Three scoops of rice: level (just right), heaped (overfilled, too much), and half full (underfilled, too little).
  • If you overfill (heap each scoop), each scoop holds more than one unit. The container fills up with fewer scoops, so your count is too small.
  • If you underfill (each scoop not full), each scoop holds less than one unit. You need more scoops, so your count is too big.
  • Also, fill the container to the top. If you stop early, your count will be too small.
Worked example

Example 2: What went wrong?

Amir measured a vase. He only filled his cup halfway each time. He counted 10 cups. Is the real capacity more or less than 10 cups?

  1. Each half cup is less than a full unit.
  2. So it took more pours than it should to fill the vase.
  3. 10 half cups is the same as 5 full cups.

His count of 10 is too big. The vase really holds about 5 full cups.

Gaps between units

Some people try to measure the capacity of a box by filling it with objects, like balls or blocks. Big round objects leave gaps (empty spaces) between them. The box could hold more, so the count is too small.

Things like water, sand or rice pour into every space. They give a much better measure of capacity.

balls leave gapsrice fills the spaces
Left: balls in a box leave empty spaces between them. Right: rice fills the box with no gaps.

Same container, different units

A jug holds 4 big mugs of water. Lily measures the same jug with a small cup and gets 8 cups.

Did the jug get bigger? No! The small cup is smaller, so it takes more of them. The capacity of the jug stays the same. Only the count changes.

4 big mugs8 small cupssame jar
The same jar measured two ways: 4 big mugs or 8 small cups. Smaller units, bigger count.
Worked example

Example 3: Different units

Jo's water bottle holds 5 mugs. Al's water bottle holds 7 small cups. Can you tell whose bottle holds more?

  1. Jo and Al used different units: a mug and a small cup.
  2. A mug might hold more than a small cup, so 5 mugs could be more than 7 cups.
  3. To compare fairly, they should measure both bottles with the same unit.

No, you can't tell yet. They need to use the same unit.

Tips for accurate measuring

  • Use the same unit every time.
  • Fill the unit level: not heaped, not half full.
  • Fill the container right to the top.
  • Use something that pours and fills all the spaces, like water, sand or rice.
  • Estimate first, then check your estimate.
Just for fun

How much dirt is in a hole that is 1 metre deep?

None! A hole is empty. But its capacity is how much dirt it would take to fill it.

Hands-on activity

Kitchen capacity lab

You need: 3 containers of different sizes (a mug, a bowl, a pot), one small cup or scoop as your unit, and water or dry rice.

Grown-up note: do this at the sink, in the bathtub or outside. Wipe up spills right away so nobody slips. Keep dry rice and beans away from babies and toddlers.

  1. Line up the containers. Predict which holds the most and which holds the least.
  2. Estimate how many scoops each one holds. Write it down.
  3. Measure each one with level scoops. Write the real number next to your estimate.
  4. Order the containers from the greatest capacity to the least.
  5. Measure one container again with a bigger unit (like a mug). Did you get more or fewer? Why?

Math talk: "Which estimate was closest? What helped you make it?"

Your turn

1

What does capacity mean?

2

With the same scoop, a jar holds 8 scoops and a bucket holds 20 scoops. Which holds more? How many more?

3

Sam filled each cup only halfway. Will his count be too big or too small?

4

Nia heaped each scoop of rice. Will her count be too big or too small?

5

A jug holds 5 big cups. If you use a smaller cup, will you count more or fewer?

6

Why is rice better than marbles for measuring the capacity of a box?

7

Which has a bigger capacity: a bathtub or a mug?

More practice: warm-up

1

Name a container in your kitchen.

2

What should you do before you measure?

3

Should your scoop be heaped, level or half full?

4

To compare two containers, should you use the same unit or different units?

5

A pot holds 10 cups. Does that tell how much it holds?

More practice: on your own

1

A big mug holds the same as 2 small cups. A jar holds 6 big mugs. How many small cups does the jar hold?

2

Ana and Ben measured the same vase. Ana counted 8 scoops. Ben counted 4 scoops. Who used the bigger scoop? Explain.

3

Owen estimated his bowl holds 10 scoops. He measured 12 scoops. Was his estimate reasonable?

4

Kim stopped pouring when the pot was almost full. Is her count too big or too small?

5

Order from greatest to least capacity (same cup): sink 30 cups, pot 15 cups, kettle 7 cups, mug 1 cup.

Challenge

1

A pot holds 12 small cups. A big mug holds the same as 3 small cups. How many big mugs fill the pot?

2

Lin measured the capacity of a shoebox by filling it with tennis balls. She got 6 balls. Is 6 a good measure of how much the box can hold? What could she use instead, and why?

3

Jada's bottle holds 4 mugs. Her mug holds 3 small cups. Leo's bottle holds 10 small cups. Whose bottle holds more? Explain.

Check your understanding

Quiz

1.

What is capacity?

2.

You heap every scoop. Your count will be ...

3.

You fill each cup only halfway. Your count will be ...

4.

Which is the best thing for measuring the capacity of a box?

5.

A jar holds 3 mugs or 6 small cups. Why are the numbers different?

6.

Using the same scoop: pot = 15 scoops, bowl = 9 scoops. How many more scoops does the pot hold?

For parents and teachers

Big idea: Children use non-standard units (cups, scoops) to estimate, measure and compare capacity, and explain how overfilling, underfilling and gaps between units affect accuracy (Ontario E2.3). They also see that a smaller unit gives a larger count while the capacity itself stays the same (E2.5). Standard units like litres come in later grades.

Common difficulties:

  • Which way the error goes. Children often think "more in each scoop means a bigger number". Act it out: heaped scoops fill the pot faster, so the count goes down.
  • Comparing counts made with different units. Always ask: "Did you use the same cup?"
  • Judging capacity by height. A tall, thin glass may hold less than a short, wide bowl. Measuring settles it.

Safety: water play near the sink or tub needs a grown-up nearby; wipe spills to prevent slips. Dry rice and beans are a choking risk for babies and toddlers.

How to help: Let your child help measure while cooking: "How many scoops of rice fill this container?"