Third Term Lesson Note for Week Two
Class : Primary 3
Subject : Mathematics
Topic : Conversion of metre to centimetre and vice versa.
Duration : 80 minutes
Period : Double Periods
Reference Book :
- New Methods Mathematics for Primary Schools, Book 3 by Oredugba étal.
- Lagos State Unified Schemes of Work for Primary Schools (Primary 1 – 3).
- Online Resources
Instructional Material : Chart showing the conversion unit from centimetre to metre, add and subtract in metre and centimetre.
Learning Objectives : By the end of the lesson learners will be able to :
i. Change metres to centimetres and vice-versa.
ii. Add and subtract in metres and centimetres.
iii. Solve word problems involving addition and subtraction of Length.
Previous Knowledge : Learners are familiar with the meaning of length , unit and measuring instrument.
Content :
Conversion of length is the changing of unit of length from one unit to another.
The relationship between metre and centimetre is 100.
That is 100centimetres (cm) = 1metre (m)
A. When changing from cm to m, we divide by 100.
For example :
Since 100cm = 1m, then we divide by 100 cm.
i. 300 cm = 300 cm ÷ 100 cm = 3 m.
ii. 450 cm = 450 cm ÷ 100 cm = 4.5 m
iii. 279 cm = 279 cm ÷ 100 cm = 2.79 m
B. When converting from metres to centimetre, we multiply by 100cm.
For example :
Since 1m = 100 cm, then we multiply by 100cm.
i. 7 m = 7 × 100cm = 700 cm.
ii. 5.2 m = 5.2 × 100cm = 520 cm
iii. 9.02 m = 9.02 × 100cm = 902 cm
C. When changing from centimetre to metre and centimetre. For examples, remember that 100cm = 1m.
i. Change 120cm to metres and centimetres.
Solution :
120 cm = 100cm + 20cm
= 1m + 20cm = 1m 20cm
ii. Convert 5m 12cm into centimetres.
Solution :
5m 12cm = 500cm + 12cm
= 512 cm
Presentation Steps :
Step 1: Revision of the previous topic with the learners by asking questions
Step 2: Introduces the new topic by explaining conversion of length from one unit to another.
Step 3: Add and subtract in metres and centimetres.
Step 4: Solve word problems involving length.
Evaluation:
1. Change the following into metres and centimetres.
a. 347cm b. 505cm
2. Change the following into centimetres.
a. 2m 56cm b. 7m 61cm
3. Solve the following:
a. 6m 15cm b. 5m 45cm
+ 7m 49cm – 2m 30cm _________________ _________________
_________________ _________________
Conclusion : At the end of the lesson learners were able to answer the questions with proper monitoring
Assignment :
Do the following :
1. 2m 45cm 2. 15m 15cm
+ 5m 51cm + 25m 25cm ________________ __________________
_________________ __________________
3. 4m 39cm 4. 10m 90cm
– 1m 12cm – 6m 25cm __________________ __________________
__________________ __________________
5. Dawodu has two pieces of cloth measuring 3m 25cm and 5m 65cm. What is the total length of materials altogether?
6. Mrs Obinna bought clothing material of 18m. She cut off 7m to make dress for her self. What length is left?