Grade by Grade
E. Spatial Sense · Shapes, Position and Measurement

Comparing Mass and Capacity

E2.1 E2.2About 30 minutes
Learning goals
  • I can compare the mass of two objects by holding them or using a balance.
  • I can order 3 objects from lightest to heaviest.
  • I can compare capacity by pouring from one container into another.
  • I know that a bigger object is not always heavier.

Words to know

mass
How heavy something is.
heavier / lighter
Has more mass / has less mass.
balance (pan balance)
A tool with two sides. The heavier side goes down and the lighter side goes up. When both sides are level, the masses are the same.
capacity
How much a container can hold.
holds more / holds less
Words for comparing capacity.
full / empty / overflow
Filled to the top / nothing inside / so full that it spills over.

Your winter boots or your sneakers: which is heavier? A bathtub or a sink: which holds more water? Today we compare mass (how heavy) and capacity (how much something holds).

Comparing mass with your hands

Hold one object in each hand. Keep your arms out. The hand that feels pulled down more is holding the heavier object. The other one is lighter.

Comparing mass with a balance

A balance is like a seesaw. Put one object on each side.

  • The side that goes down is heavier.
  • The side that goes up is lighter.
  • If the sides stay level, the objects have the same mass.
A pan balance with a large apple on the lower side and a small grape on the higher side.
The side with the apple goes down, so the apple is heavier. The grape side goes up, so the grape is lighter. AI-generated image
sockapple
The apple's side went down. The apple is heavier than the sock.
blockblock
Both sides are level. These two blocks have the same mass.
Worked example

Order three objects by mass

Order a feather, an apple and a can of soup from lightest to heaviest.

  1. Compare two at a time. Put the feather and the apple on a balance. The apple goes down, so the apple is heavier than the feather.
  2. Compare the apple and the can of soup. The can goes down, so the can is heavier than the apple.
  3. So the feather is lightest, the apple is in the middle, and the can is heaviest.
  4. Check: the feather and the can on the balance. The can goes down. That agrees!

Lightest to heaviest: feather, apple, can of soup.

Surprise!

Big does not always mean heavy! A big beach ball is light. A small rock can be heavy. A big pillow is lighter than a small can of beans. You have to test, not just look.

Comparing capacity

Capacity is how much a container can hold. To compare two containers:

  1. Fill one container to the top with water, rice or sand.
  2. Pour it into the other container.
  3. If it overflows (spills over), the first container holds more.
  4. If the second one is not full, the second container holds more.
  5. If it fills the second one exactly to the top, they hold the same amount.
big jar (full)cup spills!bowl, not full
The full jar is poured into a cup and the cup overflows, so the jar holds more than the cup. Poured into a big bowl, the bowl is not full, so the bowl holds more than the jar.
Worked example

Which holds more, the jar or the cup?

Hana fills a jar with water and pours it all into a cup. The cup overflows. Which holds more?

  1. The water from the jar was too much for the cup.
  2. That means the jar can hold more water than the cup can.

The jar holds more. The cup holds less.

Worked example

Order by capacity

Order a bathtub, a cup and a sink from holds least to holds most.

  1. Think about pouring. A cup of water would not fill a sink, so the sink holds more than a cup.
  2. Water from a full sink would not fill a bathtub, so the bathtub holds more than a sink.
  3. So the cup holds the least and the bathtub holds the most.

Holds least to holds most: cup, sink, bathtub.

Tricky containers

A tall thin glass might look like it holds more than a short wide bowl, but it might not! Pour to find out.

Mass and capacity stay the same

If you squish a ball of play dough into a pancake, it has the same mass. Nothing was added or taken away. If you pour juice from a tall glass into a wide bowl, it is the same amount of juice, even though it looks different.

Just for fun

Which is heavier: a big bag full of feathers or a big bag full of rocks?

The rocks! Same size bag, but rocks have much more mass. (Try lifting a pillow and then a backpack full of books.)

Hands-on activity

Kitchen scientists

Mass:

  1. Make a balance: hang a clothes hanger from a doorknob and hook two small bags (or cups with string) on each end.
  2. Compare pairs: a spoon and an apple, a mitten and a shoe, a crayon and a block. Which side goes down?
  3. Pick 3 objects and order them from lightest to heaviest. Guess first, then test!

Capacity (in the bathtub, the sink, or outside):

  1. Collect 3 or 4 containers: a mug, a yogurt cup, a small bowl and a water bottle.
  2. Guess which holds the most.
  3. Fill one with water and pour it into another. Did it overflow, or was it not full?
  4. Order your containers from holds least to holds most.

Your turn!

1

On a balance, one side goes down. Is that side heavier or lighter?

2

A balance stays level with a toy car on one side and a block on the other. What do you know?

3

Which is heavier, a hockey puck or a ping pong ball?

4

Order from lightest to heaviest: a dog, a mouse, a horse.

5

You pour a full bottle of water into a bowl, and the bowl is only half full. Which holds more?

6

You pour a full mug into a small cup and it overflows. Which holds less?

7

Is a big balloon always heavier than a small marble?

8

You squish a ball of play dough flat. Is it lighter now?

More practice: warm-up

1

Fill in the blank: on a balance, the side that goes up holds the ___ object.

2

True or false: capacity is how much a container can hold.

3

Which is heavier: a watermelon or a grape?

4

Which holds more water: a bucket or a mug?

5

You keep pouring water into a cup after it is full. What happens?

More practice: on your own

1

A balance has a mitten on one side and a boot on the other. The boot side goes down. Which is lighter? How do you know?

2

Order from heaviest to lightest: a pencil, a backpack full of books, a lunch box.

3

You fill a yogurt cup with water and pour it into a mug. The water fills the mug exactly to the top, with no spill. What do you know?

4

Which is usually heavier: a big empty cardboard box or a small can of soup?

5

Jamal pours all the juice from a tall glass into a wide bowl. It looks like less juice. Is there really less?

Challenge

1

The block is heavier than the crayon. The book is heavier than the block. Order them from lightest to heaviest. What test could you do to check?

2

Find the mistake! Rosa says, "The tall thin glass holds more than the short wide bowl, because it is taller." What should she do to find out?

3

A full water bottle is poured into a mug, and the mug overflows. A full mug is poured into a bowl, and the bowl is not full. Which container holds the least? How do you know?

Check your understanding

Quiz

1.

On a balance, the side with the book goes down and the side with the pencil goes up. Which is heavier?

2.

You pour a full glass of milk into a jug. The jug is not full. Which holds more?

3.

Which is usually lighter?

4.

Order from holds least to holds most: bathtub, spoon, bucket.

5.

A balance has a crayon on one side and a toy truck on the other. The sides stay level. What do you know?

6.

You pour a full bowl of water into a pot. The water overflows. Which holds more?

For parents and teachers

What your child is learning: comparing and ordering objects by mass (heaviness) and capacity (how much they hold) using direct comparison: hefting in two hands, using a simple balance, and pouring (Ontario Grade 1, E2.1 and E2.2).

Common mistakes:

  • Believing bigger always means heavier. Compare a big empty box to a small full can.
  • Judging capacity by height only ("the tall glass holds more"). Pour to check.
  • When ordering 3 objects, comparing only one pair. Show how to compare two at a time and then check.

How to help: let your child help in the kitchen: "Which bag of groceries is heavier?" "Will this soup fit in that container?" Bath time is perfect for pouring experiments. Ask them to predict first, then test, then say whether their guess was right. Being wrong is part of learning, so celebrate good guesses and good checking.