Minds On

Estimate!

Part 1

The following is an image of a jug of water beside a glass. About how many glasses of water do you think the jug of water holds?

A jug of water and an empty glass. The jug is about twice as tall as the glass and twice as wide.

How could you find out how many glasses of water this jug holds?

Record your thoughts using a voice recorder, speech-to-text, or writing tool.

Part 2

Now consider a different glass.

The following image shows a jug of water and another glass.

The amount of water in the jug is the same as before.

The glass is being filled with water from the jug of water.

Let’s estimate!

About how many glasses of water do you think the jug of water holds?

How could you find out?

How does your second estimate compare with your first?

Press ‘Answer’ to reveal the How many of the smaller glasses of water could the jug fill?

I think the jug of water could fill about 4 of the smaller glasses.

Press ‘Answer’ to reveal the How could you find out how many glasses of water the jug holds?

I could find out by pouring the water out carefully to fill the glass and count how many glasses were filled.

Press ‘Answer’ to reveal the How many of the bigger glasses of water could the jug fill?

I think the jug of water could fill about 2 and a half of the bigger glasses.

Press ‘Answer’ to reveal the How could you find out how many of these glasses of water the jug holds?

I could do the same thing as before, and pour the water in to the glass, counting how many were filled.

Press ‘Answer’ to reveal the How does your second estimate compare with your first?

My second estimate is a smaller number of glasses because the glass looks like it is bigger.

Action

Capacity

Capacity is the amount a container can hold.

To compare the capacity of two containers, you can put or pour what is in one container into another.

Capacity comparison

An image of a kitchen sink and a shallow bucket.

Consider the following experiment over a sink, water table, or large bucket.

A mug with a handle and a smaller plastic cup.

This experiment needs a sink or shallow bucket and two different sized cups, such as a coffee mug and a small cup.

A coffee mug sits in the bottom of a sink and a cup is being filled to the top with water.

In the experiment, the cup is filled with water while the coffee mug sits in the sink/bucket.

A cup filled with water is being poured into a coffee mug.

After the cup has been filled with water, the water is poured from this cup into the coffee mug that is sitting in the sink.

What do you think will happen to the coffee mug?

Will the two cups hold the same amount of water?

Record your thoughts using a method of your choice.

  • If the water overflowed when it was poured into the second cup, what did that tell you about the capacity of the first container?
  • If the second cup had more space for more water, what did that tell you about its capacity?

You decide

Two students took identical cups of water, and each poured one full cup into two separate containers.

2 identical cups of water.

Student A poured their cup of water into Container 1.

The following image displays Container 1 after the water was poured into it.

A large, deep container with a small amount of water in the bottom.

Student B poured their cup of water into Container 2.

The following image displays Container 2 after the water was poured into it.

A tall thin container that is almost filled with water.

Student A said that the volume of water is the same in both containers.

Student B said Container 2 has more water.

Who do you agree with? Explain your thinking using a method of your choice.

When you are ready, press ‘Answer’ to reveal which student was correct.

Which student was correct?

Student A is correct because both cups had identical amounts of water in them to start with. The amount won’t change just because the containers are different sizes.

It just looks like there’s more water in Container 2 because it’s almost full.

If you poured the water back into the cups, both cups would still have the same amount of water.

As well, if you were to pour Container 1 into an empty Container 2, it would look just the same as it does now, proving they have the same amount of water.

Measuring capacity

Litres and millilitres are standard units that we use to measure capacity.

You can also use any objects that you have a lot of, and that are identical to measure capacity.

When measuring capacity, it is best to choose something that is small to be precise, but still large enough to count. Here are some examples:

  • spoonfuls of water
  • spoonfuls of sand
  • spoonfuls of rice
  • individual marbles
  • individual beads
  • individual unifix cubes

Can you think of other non-standard units that would be good to measure capacity?

Press ‘Cup-acity’ to complete a measuring activity. This activity is optional.

Cup-acity

A tall cup of water filling a small cup of water. A third larger cup of water is beside the small cup.

Complete the following activity and record your results. You can record the results of your experiment using a method of your choice.

  1. Choose a cup to fill with water. Select different-sized cups as non-standard measuring tools.
    • How many of the smaller cups, carefully filled, does it take to fill the first cup?
  2. Use another cup of a different size to measure.
    • How many small cup units might it take to fill the container completely this time?
    • What do you need to consider when finding capacity?
    • Did you fill the cup to the same level each time?

Answer the following questions about the experiment:

  • How can you make sure you filled your cup to the top?
  • If you fill your first cup with different kinds of cups, what did you notice?
  • How can you communicate the capacity of the first cup using different sized cups?

Underfilling and overfilling

It’s important to be accurate when making measurements. Two common ways to get an inaccurate capacity measurement are to underfill or overfill the container you are measuring.

Underfilling

A jar with 30 marbles inside. There are spaces in between the marbles.

Underfilling means that a container is not filled completely.

For example, consider the following jar that has been filled to the top with 30 marbles.

The space between the marbles tells us that the jar is underfilled.

What could we use instead of marbles that would create fewer or no gaps?

Overfilling means that a container can’t hold everything: it overflows.

For example, consider the following cup of rice. The cup has been filled past its rim using spoonfuls of rice.

The rice above the rim of the cup lets us know that it has been overfilled.

A cup that is overflowing with rice. There are 8 spoons filled with rice beside it.

Your turn

The following image displays seven bottles that are different sizes.

How could you use the liquid in each bottle to help figure out which bottle holds the most liquid (has the greatest capacity)?

Various brightly coloured plastic bottles.

Now examine the following bucket.

If we wanted to measure the capacity of the bucket, explain how we could use the bottles to help figure out how much liquid the bucket holds.

Red toy bucket on lawn.

Hint: Remember to use the same unit when measuring. You could measure in cups or in spoons.

When you are ready, press ‘Answers’ to reveal possible responses to the questions.

How could you use the liquid in each bottle to help figure out which bottle holds the most liquid (has the greatest capacity)?

We could use the liquid in each bottle to help figure out which bottle holds the most liquid by emptying all the bottles except one.

We would choose the bottle that we thought was either the greatest capacity or the least. We would fill the bottle up and then empty it into the other bottles.

If the water overfilled the bottle, we would know that the original bottle had a greater capacity.

If it underfilled, then we would know the original bottle had a lesser capacity.

We would do this until we got them all in order.

If we wanted to measure the capacity of the bucket, explain how we could use the bottles to help figure out how much liquid the bucket holds.

If we wanted to measure the capacity of the bucket, we would choose a single bottle to help figure out how much liquid the bucket holds. We could then count the number of bottles it takes to fill the bucket.

Consolidation

Container comparison

A child is pouring chocolate milk from one cup into another cup. A third cup is beside the child.

Choose three containers that appear to have similar capacities.

Choose three non-standard units to measure the capacity of the containers you chose.

For each non-standard unit, estimate then measure and record the capacity of each container.

Determine which container had the largest and smallest capacity.

Alternatively, create a detailed description about a container you would choose, and record how to accurately assess the capacity in an audio recording or written response.

You can record your responses in the following fillable and printable Container Comparison document. You can also complete this activity in your notebook or use another method.

Container Comparison

Press the Activity button to access Container Comparison.

Activity (Open PDF in a new tab)

Think about your learning

  • Is it more precise to measure capacity using smaller units or larger units?
  • How does overfilling and underfilling affect the accuracy when measuring capacity?

Reflection

How do you feel about what you have learned in this activity? Which of the next four sentences best matches how you are feeling about your learning? Press the button that is beside this sentence.

I feel...

Now, record your ideas about your feelings using a voice recorder, speech-to-text, or writing tool.