Lesson Plan of Subtraction up to 100
Subject Mathematics
Grade III
Students` Learning Outcomes
- Subtract numbers up to 100 using mental calculation strategies.
Information for Teachers
- Mental calculation is a skill that not only helps us to become better at computation but it also enhances the development of number concepts.
- Using mental calculation, we subtract the numbers by some shortcut methods without solving it on paper.
- While teaching the lesson, also consult textbook where and when applicable.
Material / Resources
Writing board, chalk/marker, duster, Mathematics textbook
Introduction
- Write on the board:
- Ask the students` can you solve it mentally?
- Collect their feedback and tell them that we have a simple method to solve it mentally.
- First break up the numbers into ‘tens’ and ‘ones’.
- Ask any student to tell how many ‘tens’ and ‘ones’ in 25 and 12.
25 = 2 tens + 5 ones
12 =- 1 ten + 2 ones
- Tell the students to subtract ones from ones and tens from tens.
2 tens – 1 ten = 1 ten
5 ones – 2 ones = 3 ones
- In the end write the two answers as:
1 ten 3 ones = 13
- The required answer is 13.
- Tell the students that let us practice some more questions.
Development
Activity 1
- Write on the board:
- Ask the students to solve this question mentally.
- Collect their feedback and ask any student to write the strategy on the board like this.
58 = 5 tens + 8 ones
26 = 2 tens + 6 ones
- Subtract tens from tens i.e. 5 – 2 = 2
- Subtract ones from ones i.e. 8 – 6 = 2
- Now first write ‘tens’ and then ‘ones’ (from left to right) i.e. 32
- Repeat this activity for some more numbers by involving maximum students.
Activity 2
- Write 76 – 27 on the board.
- Tell the students that let us solve this question mentally by another easier method.
- First make the subtrahend i.e. 27 to the closest tens i.e. 10, 20 or 30.
- We observe that 27 is closer to 30, so make 27 to 30.
- Add 3 to 27 to make it 30.
- Now subtract the new numbers: 79 – 30 = 49
- The required answer is 49.
- Repeat the procedure to solve the question.
Activity 3
- Write the following questions on the board:
- Ask the students to solve these questions using mental calculation.
- Write the correct answers on the board.
- Also repeat the strategy to solve these questions.
Sum up / Conclusion
- First break up the numbers into ‘tens’ and ‘ones’. .then subtracts tens from tens and ones from ones.
- In the end, first write tens and then ones (from left to right).
Assessment
- Write the questions on the board:
- Ask the students to solve the questions mentally.
- Collect their answers and appreciate them.
Follow up
- Aslam has Rs. 100. He bought colour pencil box for Rs. 56. Calculate mentally and find how much money is left with him?
- Ask the students to solve the questions given in the textbook.
