Mathematics Class 5 - Measurement Of-Length Notes

Measurement of Length

Welcome to the chapter on Measurement of Length for Class 5. In this chapter, you will learn how to measure length, the units we use, how to convert between units, and how to solve word problems. By the end of this chapter, you will be able to measure and compare lengths confidently!

Introduction

Measurement of length helps us know how long, tall, or wide something is. We use different tools and units to measure length in our daily life.

Units of Length

• Millimeter (mm): Smallest unit, used for tiny objects.
• Centimeter (cm): Used for small objects like pencils.
• Meter (m): Used for measuring rooms, height, etc.
• Kilometer (km): Used for long distances like roads.

Tools for Measuring Length

• Ruler (for cm and mm)
• Measuring tape (for cm and m)
• Meter scale (for m)
• Odometer (for km in vehicles)

Converting Units

• 10 mm = 1 cm
• 100 cm = 1 m
• 1000 m = 1 km

To convert from a bigger unit to a smaller unit, multiply. To convert from a smaller unit to a bigger unit, divide.

• 5 m = 500 cm (multiply by 100)
• 3000 m = 3 km (divide by 1000)

Addition and Subtraction of Lengths

You can add or subtract lengths using the same units.

• Example: 125 cm + 75 cm = 200 cm
• Example: 2 m - 50 cm = 150 cm (convert 2 m to 200 cm first)

Word Problems

Use measurement of length to solve real-life problems. Read the question, choose the correct units, and solve.

• Example: A rope is 3 m long. Another rope is 150 cm long. What is their total length in cm? (3 m = 300 cm, 300 cm + 150 cm = 450 cm)

Fun Activity: Measure and Compare!

Use a ruler or measuring tape to measure objects at home. Compare their lengths and write them down!

Summary

• Length tells us how long, tall, or wide something is.
• We use mm, cm, m, and km to measure length.
• Convert units carefully and solve word problems using length.

Practice Questions

1. Convert: 5 m = ____ cm
2. Add: 250 cm + 175 cm
3. Subtract: 3 km - 1500 m (give answer in meters)
4. Which tool will you use to measure your desk?
5. Solve: A stick is 120 cm long. Another stick is 1 m long. What is their total length in cm?

Challenge Yourself

• Make your own word problem using two different units of length.
• Measure the length of your classroom and write it in meters and centimeters.

Did You Know?

• The longest river in India is the Ganga, which is over 2,500 km long!
• A marathon race is 42.195 km long!

Glossary

• Length: How long something is.
• Unit: A standard amount used for measuring.
• Convert: Change from one unit to another.
• Ruler: A tool used to measure small lengths.

Answers to Practice Questions

1. 500 cm
2. 425 cm
3. 3 km = 3000 m; 3000 m - 1500 m = 1500 m
4. Ruler or measuring tape
5. 120 cm + 100 cm = 220 cm

---

Practice measuring and converting lengths to become a measurement expert!