Year 5 Maths: Converting Units of Lengths

Introduction to Lengths

Hello, Year 5! Today, we’re going to learn about something very important in maths: converting units of lengths. This means changing a measurement from one unit to another.

What is Length?

Length tells us how long something is. We can measure length in different units, such as:

• Millimetres (mm)
• Centimetres (cm)
• Metres (m)
• Kilometres (km)

Understanding Units

1. Millimetres (mm): These are very small measurements. There are 10 millimetres in a centimetre.
2. Centimetres (cm): A bit bigger than millimetres. There are 100 centimetres in a metre.
3. Metres (m): Commonly used for measuring things like a room or a desk.
4. Kilometres (km): Used for longer distances, like how far away a park is.

Key Rules for Converting Units of Length

1. From smaller to larger units, we divide:
   • To convert from millimetres to centimetres, divide by 10.
   • To convert from centimetres to metres, divide by 100.
   • To convert from metres to kilometres, divide by 1,000.
2. From larger to smaller units, we multiply:
   • To convert from kilometres to metres, multiply by 1,000.
   • To convert from metres to centimetres, multiply by 100.
   • To convert from centimetres to millimetres, multiply by 10.

Examples

1. Converting from cm to m:
   • If you have 250 cm, to convert to metres, you divide by 100.
   • $$250 \div 100 = 2.5 m$$
2. Converting from m to cm:
   • If you have 3 m, to convert to centimetres, you multiply by 100.
   • $$3 \times 100 = 300 cm$$

Tips and Tricks

• Remember the order: Smaller units are on the left and larger units are on the right. Use this to guide your conversions.
• Use a ruler: Measuring with a ruler can help you see how these conversions work in real life.
• Practice makes perfect: The more you practice converting, the easier it will become!

Questions for Practice

Easy Level Questions

1. Convert 20 cm to mm.
2. Convert 1 m to cm.
3. Convert 500 mm to cm.
4. Convert 2 m to mm.
5. Convert 3 km to m.
6. Convert 150 cm to m.
7. Convert 75 mm to cm.
8. Convert 5 m to cm.
9. Convert 10 mm to cm.
10. Convert 250 m to km.

Medium Level Questions

11. Convert 300 mm to m.
12. Convert 4 km to m.
13. Convert 600 cm to mm.
14. Convert 7 m to km.
15. Convert 1.5 km to m.
16. Convert 900 mm to cm.
17. Convert 2.2 m to cm.
18. Convert 1 m 50 cm to cm.
19. Convert 5 km 500 m to m.
20. Convert 0.75 km to m.

Hard Level Questions

21. Convert 3 m 25 cm to mm.
22. Convert 4.5 km to cm.
23. Convert 1500 mm to m.
24. Convert 2.75 km to m.
25. Convert 1.2 m to mm.
26. Convert 500 cm to km.
27. Convert 2 m 10 cm to cm.
28. Convert 1250 mm to km.
29. Convert 3.6 km to m.
30. Convert 2 m 50 cm to mm.

Answers and Explanations

Easy Level Answers

1. 20 cm to mm: $$20 \times 10 = 200 mm$$
2. 1 m to cm: $$1 \times 100 = 100 cm$$
3. 500 mm to cm: $$500 \div 10 = 50 cm$$
4. 2 m to mm: $$2 \times 1000 = 2000 mm$$
5. 3 km to m: $$3 \times 1000 = 3000 m$$
6. 150 cm to m: $$150 \div 100 = 1.5 m$$
7. 75 mm to cm: $$75 \div 10 = 7.5 cm$$
8. 5 m to cm: $$5 \times 100 = 500 cm$$
9. 10 mm to cm: $$10 \div 10 = 1 cm$$
10. 250 m to km: $$250 \div 1000 = 0.25 km$$

Medium Level Answers

11. 300 mm to m: $$300 \div 1000 = 0.3 m$$
12. 4 km to m: $$4 \times 1000 = 4000 m$$
13. 600 cm to mm: $$600 \times 10 = 6000 mm$$
14. 7 m to km: $$7 \div 1000 = 0.007 km$$
15. 1.5 km to m: $$1.5 \times 1000 = 1500 m$$
16. 900 mm to cm: $$900 \div 10 = 90 cm$$
17. 2.2 m to cm: $$2.2 \times 100 = 220 cm$$
18. 1 m 50 cm to cm: $$1 \times 100 + 50 = 150 cm$$
19. 5 km 500 m to m: $$5 \times 1000 + 500 = 5500 m$$
20. 0.75 km to m: $$0.75 \times 1000 = 750 m$$

Hard Level Answers

21. 3 m 25 cm to mm: $$3 \times 1000 + 25 \times 10 = 3250 mm$$
22. 4.5 km to cm: $$4.5 \times 1000 \times 100 = 450000 cm$$
23. 1500 mm to m: $$1500 \div 1000 = 1.5 m$$
24. 2.75 km to m: $$2.75 \times 1000 = 2750 m$$
25. 1.2 m to mm: $$1.2 \times 1000 = 1200 mm$$
26. 500 cm to km: $$500 \div 100000 = 0.005 km$$
27. 2 m 10 cm to cm: $$2 \times 100 + 10 = 210 cm$$
28. 1250 mm to km: $$1250 \div 1000000 = 0.00125 km$$
29. 3.6 km to m: $$3.6 \times 1000 = 3600 m$$
30. 2 m 50 cm to mm: $$2 \times 1000 + 50 \times 10 = 2050 mm$$

Now you have everything you need to understand converting units of lengths! Keep practicing, and you’ll be a pro in no time!