# Lesson Plan of Subtraction up to 100

## 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.

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