Length – Non-standard and standard measurement; Measuring in centimetres and metres; Real-life applications; Counting numbers 841–860 For Primary 3

Subject: Mathematics

Class: Primary 3

Topic:

• Length: Non-standard and Standard Measurement

• Measuring in Centimetres and Metres

• Real-life Applications

• Counting Numbers 841–860

Term: Third Term

Week: 2

Duration: 40 minutes

A. Lesson Objectives

By the end of the lesson, pupils should be able to:

1. Differentiate between non-standard and standard units of length.

2. Identify centimetres (cm) and metres (m) as standard units of length.

3. Measure objects using centimetres and metres correctly.

4. Apply the concept of length in real-life situations.

5. Count, read, and write numbers from 841 to 860.

B. Instructional Materials

• Ruler (for measuring in cm)

• Metre rule or measuring tape

• Classroom objects (books, tables, pencils, etc.)

• Flashcards with numbers 841–860

• Charts showing standard and non-standard units

C. Lesson Content

1. What is Length?

Length is how long or short something is.
We use length to measure how far, tall, or wide things are.

2. Non-standard Units of Measurement

These are measurements using objects instead of real measuring tools.

Examples:

• Hand span

• Footstep

• Arm length

• Cubit (elbow to finger)

These units are not the same for everyone. They are not accurate for important measurements.

3. Standard Units of Measurement

Standard units are used by everyone and give accurate results.

Two main standard units for length:

100 centimetres = 1 metre

4. Tools for Measuring Length

• Ruler – used to measure in centimetres

• Measuring tape – used for cm and metres

• Metre rule – used to measure in metres

5. Measuring in Centimetres and Metres

Example 1:
Measure the length of a book using a ruler:
👉 The book is 25 cm long.

Example 2:
Measure the height of the classroom door with a metre rule:
👉 The door is 2 metres tall.

6. Real-life Applications of Length Measurement

We use length in daily life to:

• Buy cloth (in metres)

• Measure height or distance

• Measure tables, books, or doors

• Build houses and roads

7. Counting Numbers from 841 to 860

Let’s count from 841 to 860:

841, 842, 843, 844, 845, 846, 847, 848, 849, 850,
851, 852, 853, 854, 855, 856, 857, 858, 859, 860

Reading and Writing Numbers:

• 841 → Eight hundred and forty-one

• 850 → Eight hundred and fifty

• 860 → Eight hundred and sixty

D. Class Activities

Activity 1: Measuring Practice

Let pupils use rulers and measuring tapes to measure items around them (e.g., pencils, books, tables).

Activity 2: Real vs Non-standard

Give two objects to measure using hand spans and then measure the same with a ruler. Compare results.

Activity 3: Counting Game

Have pupils stand in a circle and count from 841 to 860, one after another.

E. Evaluation (Assessment)

Ask pupils:

1. What is the difference between standard and non-standard measurement?

2. Name two tools used for measuring length.

3. How many centimetres make one metre?

4. What is the length of your pencil in cm?

5. Write the numbers from 855 to 860.

F. Assignment

1. Measure and write the length (in cm) of:

   • Your book

   • Your shoe

   • Your desk

2. Write the numbers from 841 to 850 in words.

G. Conclusion

• Length helps us to know how long or short things are.

• We can measure using non-standard units (like hand spans) or standard units (like cm and m).

• We use length measurements in real life every day.

• We can count and write numbers from 841 to 860.