Mass & capacity
🎯 In this topic you will
- Explore and compare the mass of different objects.
- Explore and compare the capacity of different containers.
🧠 Key Words
- capacity
- empty
- full
- heavy
- light
- mass
Show Definitions
- capacity: The maximum amount of liquid a container can hold.
- empty: Describes a container that has nothing inside it.
- full: Describes a container that is filled to its maximum level.
- heavy: Having a large mass compared with another object.
- light: Having a small mass compared with another object.
- mass: The amount of matter in an object, usually measured in grams or kilograms.
⚖️ Understanding Mass and Weight
The more mass an object has, the heavier it is.
🥤 What Capacity Means
Capacity is how much an object can hold.
🫗 Comparing Container Capacity
This jug can hold more water than the cup. It has a bigger capacity.
❓ EXERCISES
1. Talk to your partner. Which is heavier? Which is lighter? How do you know?
👀 Show answer
• The shoe is heavier than the feather.
• The brick is heavier than the ball.
• The duck is heavier than the snail.
We know by comparing their mass or by thinking about real-life weight.
2. Talk to your partner. Which is heavier? Which is lighter? How do you know? Draw a ring around the correct answer.
👀 Show answer
Bottom row: The group with fewer cubes is lighter.
We compare by counting the number of equal cubes.
3. Draw a ring around the correct word.
👀 Show answer
b. heavier than
4. To balance the scales you need the same mass on both sides. How many cubes will balance the car and the mug?
👀 Show answer
Mug = $7$ cubes.
Total needed = $11$ cubes.
5. Draw a ring around the objects that hold the most in each box.
👀 Show answer
🧠 Think like a Mathematician
Let’s investigate: Work on your own.
You will need:
- $5$ cups of the same size and shape.
- $6$ cups in different sizes and shapes.
- A jug, a funnel and some rice.
Challenge $1$
Use cups that are the same shape and size.
Share out all the rice equally between the cups.
Draw a line on the side of the cups to show where the rice comes to.
Talk about how you can share out the rice equally.
Challenge $2$
Repeat the challenge using cups of different sizes.
What do you notice?
Did you change your mind about the way you shared the rice?
If you did this again, would you do it the same or differently? Explain why.
👀 show answer
- What do you notice? With the same cups, the rice reaches the same height in every cup when you share it equally. With different-sized cups, equal sharing means each cup gets the same amount of rice, but the heights can be different because the cups have different widths.
- Did you change your mind about the way you shared the rice? You might realise that “equal” means the same amount, not the same height. So you may need a better method than just matching the line height when cups are different.
- Would you do it the same or differently? Explain why. Differently: you could measure equal amounts (for example, using the same scoop each time or pouring into a measuring cup) so each cup gets the same quantity even when the cups are different shapes.
❓ EXERCISES
6. Solve the puzzle to help the king find his drink.
Match the jugs to the characters.
The kangaroo drinks the jugs that are full.
The mouse has $3$ empty jugs.
The rabbit has $2$ empty jugs.
The king drinks more than the mouse but less than the girl.
The girl drinks less than the kangaroo. [Join the girl to B]
Does the king drink A B C D E?
Draw a ring around the correct answer.
👀 Show answer
Mouse → group with $3$ empty jugs.
Rabbit → group with $2$ empty jugs.
Girl → B.
King → C (more than the mouse but less than the girl).