# Minds On

## How many units?

Examine the following pumpkin patch.

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

Now explore the following image of water containers.

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

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:

• 1,000 grams is equal to 1 kilogram

The milk benchmark helps us understand that:

• 1,000 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

### 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

### 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

### 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

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

1 paperclip labeled 1 gram beside a jar of 1,000 paperclips labeled 1 kg. You would need 1,000 paperclips to make 1 kg.

This benchmark helps us to understand that:

• 1,000 grams is equal to 1 kilogram

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

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

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