Minds On

How many units?

Examine the following pumpkin patch.

How many kilograms of pumpkins do you think are in the patch?

A pumpkin field. There are several rows of large pumpkins

Now explore the following image of water containers.

How many litres of water do you think is in the largest water bottle?

5 water containers, arranged from smallest to biggest. The biggest water container is about the size of a backpack

How can we determine the mass or capacity of an object or container if we cannot measure?

Record your ideas in a notebook or a method of your choice.

Action

Estimating mass and capacity

How do we know the mass of an item, the capacity of a container, or the length of an item without measuring it?

We can estimate.

Estimating is using our prior knowledge to help us come up with a close guess or idea. We can use benchmarks to help us estimate measurements in length, mass, and capacity.

Explore the following benchmarks.

The paperclip benchmark helps us understand that:

  • 1000 grams is equal to 1 kilogram

The milk benchmark helps us understand that:

  • 1000 millilitres is equal to 1 litre

When we try our estimates, using this information is important so that we can determine if the mass or capacity is measured in smaller units (grams or milligrams) or larger units (kilograms and litres).

Let’s estimate!

Once we have a benchmark, it gives us the opportunity to estimate more accurately.

Let’s practice estimating with benchmarks.

Using the following benchmarks, choose the estimate which seems the most accurate.

Estimate the mass: carrots

Explore the following chart. It displays a group of carrots with an unknown mass and a benchmark that we can use to measure the mass of the carrots.

Benchmark item Group of carrots
Small carrot with a mass of 50 grams A group of about 40 carrots. What is the mass?

Use the benchmark to help you select the most accurate estimate.

Estimate the mass: cars

Explore the following chart. It displays a group of cars with an unknown mass and a benchmark that we can use to measure the mass of the cars.

Benchmark item Group of cars
A car with a mass of 1302 kilograms. A group of 5 cars. What is the mass?

Use the benchmark to help you select the most accurate estimate.

Estimate the mass: orange juice

Explore the following chart. It displays a pitcher of orange juice with an unknown amount and a benchmark that we can use to measure the amount of juice in the pitcher.

Benchmark item Pitcher of orange juice
A 200 millilitre glass of orange juice. There is an orange beside the glass. A pitcher of orange juice with an orange beside the pitcher. What is the amount of juice?

Use the benchmark to help you select the most accurate estimate.

Estimate the mass: vegetable oil

Explore the following chart. It displays three containers of vegetable oil with an unknown amount and a benchmark that we can use to measure the amount of oil.

Benchmark item Three containers of vegetable oil
A 2 litre container of vegetable oil. Three containers of vegetable oil. What is the amount of oil?

Use the benchmark to help you select the most accurate estimate.

Brainstorm

Let's reflect

Reflect on this activity by responding to the following question. You can record your thinking using a method of your choice.

How did you decide which estimation was most accurate?

Consolidation

Let’s practice!

Let’s use our estimation skills to complete the following activities. You will be using the benchmarks and your prior knowledge.

Press the ‘Benchmarks’ button to reveal our benchmarks for grams to kilograms and millilitres to litres. You can use these benchmarks to help complete the activities in this section.

Benchmarks

The following benchmark for mass; one paper clip is 1 gram, and 1000 paper clips is 1 kilogram.

There is 1 paperclip is labelled 1 gram beside a jar of 1,000 paperclips labelled 1 kilogram. 1,000 paperclips are equal to 1 kilogram.

This benchmark helps us to understand that:

  • 1,000 grams is equal to 1 kilogram
The following benchmark for capacity; a spoon of milk is 1 millilitre and a jug of milk is 1 litre. 1000 spoons of milk is 1 litre of milk.

A spoon of milk labeled 1 millilitre beside a jug of milk labeled 1 litre. 1,000 spoons of milk make 1 litre of milk.

This benchmark helps us to understand that:

  • 1,000 millilitres is equal to 1 litre

Which is it?

Select the best estimate for each of the following objects.

Brainstorm

Explain your thinking

How did you determine which estimate was most accurate? Explain your thinking using a method of your choice.

Which is it?

Let’s try again! This time, we will be estimating the capacity of different containers.

Select the best estimate for each of the following containers.

Brainstorm

Explain your thinking

How did you determine which estimate was most accurate? Explain your thinking using a method of your choice.

Think about your learning

Answer the following questions using a method of your choice.

  • How does using a benchmark help in making estimates?
  • What are some other strategies we can use to estimate mass or capacity?

Reflection

As you read through these descriptions, which sentence best describes how you are feeling about your understanding of this learning activity? Press the button that is beside this sentence.

I feel...

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