Minds On
Metric measurements
Explore the following video entitled “Metric Measurements” to learn about metric units of measurement.
Brainstorm
Thinking in metric units
Explore the following images. Then, think about which metric unit you would use to measure each object.
Which metric unit would you use to measure this pencil? Why?
- 1 millimetre
- 1 centimetre
- 1 metre
- 1 kilometre
Which metric unit would you use to measure this picture frame? Why?
- 1 millimetre
- 1 centimetre
- 1 metre
- 1 kilometre
Which metric unit would you use to measure this table? Why?
- 1 millimetre
- 1 centimetre
- 1 metre
- 1 kilometre
Which metric unit would you use to measure this basketball court? Why?
- 1 millimetre
- 1 centimetre
- 1 metre
- 1 kilometre
Action
What are metric units?
We use metric units when we measure length and distance. Depending on the object or the space that we want to measure, we can use the following units:
- millimetres (mm)
- centimetres (cm)
- metres (m)
- kilometres (km)
Measurement rules!
Examine the following ruler. Which metric units do you notice?
Rulers often have two metric units: millimetres (mm) and centimetres (cm).
The length between two short lines on the ruler is one millimetre. The longest lines and numbers keep track of the centimetres.
Brainstorm
Examining a ruler
Let’s find out how many millimetres are equal to one centimetre.
Examine the following section of a ruler:
Answer these two questions, and record your responses using a voice recorder, speech-to-text, or writing tool:
- How many millimetres are in one centimetre?
- Why are some lines longer than others?
Let’s sum up…
There are 10 millimetres in a centimetre.
On a metric ruler, the shortest lines mark millimetres. Medium-sized lines mark every five millimetres (or half of a centimetre). Long lines mark every 10 millimetres (or 1 centimetre). This makes it easier for us to measure without needing to count every little line. Some rulers have raised lines and numbers in order to identify each value.
The following image shows the marks on a ruler.
Measuring items
Student Tips
Using benchmarks
What do you do when you want to measure something, but don’t have any measuring tools available? In this case, you can use benchmarks. Benchmarks help us estimate.
- The thickness of a library card, or 10 sheets of paper stacked together, is about 1 millimetre.
- The width of a fingertip is about 1 centimetre.
- The width of a doorway is about 1 metre.
Measurement practice
Part 1
Use a measuring device of your choice to measure the length of 3 to 5 different items. Before you measure, make an estimate using a benchmark. Don’t forget to start your measuring at 0.
You can also describe how you would measure items in writing or an audio clip. Some things you may measure are:
- the length of a paperclip
- the length of a pencil
- the width of a staple
Part 2
Record your ideas using a method of your choice.
- What did you measure using millimetres?
- What did you measure using centimetres?
We can measure length and distance using different units. Using different-sized units gives a different number, but does not change the length or distance measured.
For example, how long is a pencil in centimetres? Now what is the length in millimetres? What do you notice?
We rule!
Use a ruler to help you answer these questions.
Test Your Skills!
Test your skills
Create and answer a question that is similar to the ones we just explored.
Converting between metric units
When you change from one unit to another, this is called converting. The number changes, but the actual length stays the same.
Converting between centimetres and millimetres
The key is to remember that there are 10 millimetres in 1 centimetre.
Converting from centimetres to millimetres
When converting from centimetres to millimetres, multiply the measurement by 10 because there are ten millimetres in every one centimetre.
The following example shows how to express 5 cm in millimetres.
Converting from millimetres to centimetres
When converting from millimetres to centimetres, divide the measurement by 10 because one centimetre is made up of 10 millimetres.
The following example shows how to express 80 mm in centimetres.
Metre measurements
Explore the following video entitled “Measurement” in which Teacher Troy gives tips on measuring lengths in metric units.
After exploring the video, review your learning by answering the following question:
In the video, Teacher Troy explored a metre stick. As he explained, a metre stick measures 100 cm, and is one metre long. There were markers on the metre stick to indicate each centimetre.
Test Your Skills!
Metre stick mission!
Using a measuring device of your choice, measure the length of different items. Record your responses using a method of your choice. If you prefer, you can create a detailed description about how you would use a measurement device to measure the length and width of different items.
How might a metre stick, a ruler, a digital tool, or other measuring devices be helpful to measure the length of and distance between things in your environment? Some things you may measure are…
- the length from one end of the room to the other
- the length of a desk
- the height of a door
- the height of a chair
Consider the following questions:
- What did you measure using metres?
- What did you measure using centimetres?
We can measure length and distance using different units. Using different-sized units produces a different count, but does not change the length or distance that was measured.
So, we meet again!
Answer the following questions:
- How many centimetres are in 2 metres?
- How many metres are equal to 300 centimetres?
- How might you find the answers?
Let’s share!
- When you converted from metres to centimetres, did you multiply or divide? By how much?
- When you converted from metres to centimetres, did you add or take away zeros? How many?
When you are ready, press ‘Answers’ to reveal the solutions to these questions.
- 2 metres = 200 cm
- 300 cm = 3 metres
- I could use a metre stick to find the answer for 1 metre, and then double/triple to find 2 metres and 300 cm. Or, I can multiply by 10 when trying to figure out how many centimetres are in 1 metre, or divide by 10 when I want to know how many metres are represented by a number of centimetres.
Converting between metres and centimetres
The key is to remember that there are 100 centimetres in 1 metre.
Converting from metres to centimetres
When converting from metres to centimetres, you multiply the measurement by 100 because there are 100 centimetres in a metre. There are 100 times the number of centimetres as metres.
The following example shows how to express 6 metres in centimetres.
Converting from centimetres to metres
When converting from centimetres to metres, you divide the measurement by 100 because a metre is made up of 100 centimetres.
The following example shows how to express 700 centimetres in metres.
When you divide by 100, you remove two zeros from the number you started with.
Carried away with kilometres
Kilometres are used to measure longer distances. We do not have a measuring device like a ruler, metre stick, measuring tape, or trundle wheel to help measure kilometres.
There are 1,000 metres in 1 kilometre.
We use kilometres to measure the distance between towns, cities, and even countries!
It would take 12 minutes on average to travel a single kilometre.
Brainstorm
Questions about kilometres
Respond to the following questions. Use a method of your choice to record your answers.
- Can you think of two places that are about a kilometre apart?
- How do you decide when to use kilometres instead of metres?
Practising conversion
You will now practise converting between different units of measure.
Complete the Conversion Practice activity in your notebook or using the following fillable and printable document. You can also complete this activity using another method of your choice to record your answers.
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Conversion Practice |
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7 cm = (Blank) mm |
90 mm = (Blank) cm |
800 cm = (Blank) m |
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9 m = (Blank) cm |
5 km = (Blank) m |
6,000 m = (Blank) km |
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(Blank) mm = 2 m |
3 km = (Blank) cm |
4 km = (Blank) mm |
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Now come up with some of your own questions: |
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Press the ‘Activity’ button to access Conversion Practice.
Brainstorm
Thinking about conversion
Consider these questions and be ready to share!
What strategy did you use to convert between the following?
- millimetres and metres
- centimetres and kilometres
- millimetres and kilometres
- Can you think of a reason you would want to convert between millimetres and metres?
When you are ready, press ‘Answers’ to reveal the answers to the Conversion Practice activity.
| 7 cm = 70 mm | 90 mm = 9 cm | 800 cm = 8 m |
| 9 m = 900 cm | 5 km = 5,000 m | 6,000 m = 6 km |
| 2,000 mm = 2 m | 3 km = 300,000 cm | 4 km = 4,000,000 mm |
Consolidation
Measure and convert
You will now measure three different items using millimetres, centimetres, and metres. Then, you will convert each measurement to one other unit.
How would you measure each item of your choice, and what measuring tool would be most effective?
Complete the Measure and Convert activity in your notebook or using the following fillable and printable document. You can also complete this activity using another method of your choice. For example, you can create a detailed written, typed, or audio description about your ideas.
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Measure and Convert |
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Step 1: Find something to measure in millimetres. Then convert the measurement to EITHER centimetres OR metres. |
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Item measured |
Length in mm |
Length in cm |
Length in m |
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Step 2: Find something to measure in centimetres. Then convert the measurement to EITHER millimetres OR metres. |
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Item measured |
Length in cm |
Length in mm |
Length in m |
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Step 3: Find something to measure in metres. Then convert the measurement to EITHER millimetres OR centimetres. |
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Item measured |
Length in m |
Length in mm |
Length in cm |
Press the ‘Activity’ button to access Measure and Convert.
Think about your learning
- How are benchmarks helpful?
- How do you decide which unit of measurement makes the most sense to use? Share an example to support your response.
- Are there times when more than one unit is appropriate to use? Share an example to support your response.
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.