Lesson Plan of Subtraction of Units of Length
Subject Mathematics
Grade III
Students` Learning Outcomes
- Subtract measures of length in same units with and without borrowing.
- Solve real life problems involving same units of length for subtraction with and without carrying.
Information for Teachers
- Question should be written vertically under column headings (km, m, and cm).
- Write large value in upper row and small value in bottom now.
- To find the difference of lengths, centimeters are subtracted from centimeters, meters from meters and kilometers from kilometers.
- If one of the columns has a smaller number on top, the number borrows from the number to its left.
- While teaching the lesson, also consult textbook where and when applicable.
Material / Resources
Writing board, chalk/marker, duster, paper strips` chart (Relation of the nits and subunits of length)
Introduction
- Ask from students:
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- If a string is 5 meter long and someone cut 3 meter out of it. What length of the string is left now? (2cm)
- Ali`s height is 1m 23cm and his father’s height is 1m 86cm. how much father is taller than Ali? (63cm)
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Development
Activity 1
- Write the following statement on the board.
- Ask following questions from the students and write their answers on board.
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- What is the length of pencil before sharpening? (14cm)
- How much length is reduced ?(2cm)
- Which operation can be used to find the new length of the pencil? (subtraction)
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- Demonstrate how to solve this problem.
- Write another statement on board.
- Ask one of the students, what is the total distance? (14cm 149m)
- Ask the students to write 4km 149m on board under column headings (km and m)
- Ask another student, how much distance does Hassan travel by bus? (3km 218m)
- Ask the student to write 3km 218m under the first value.
- Ask another student, which operation can be performed to find the distance covered on foot? (subtraction)
- Explain it to the students, subtraction of units of length is same as the subtraction of whole numbers.
Activity 2
- Write the question of subtraction of some lengths with and without borrowing, on both sides of paper strips.
- Distribute paper strips to all students.
- Ask students to solve the given questions.
- Take a round in a class and observe their work.
- Guide them where necessary.
- Call volunteer students to share them work on board with the whole class.
Sum up / Conclusion
- Conclude that:
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- To find the difference between the lengths of two different objects, centimeters are subtracted from centimeters, meters from meters and kilometers from kilometers.
- When we borrow 1km from kilometers column, it is equal to 1000m and add 1000m into the meters column.
- When we borrow 1m from meters column, it is equal to 100cm and add 100cm into the centimeters column.
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Assessment
- Ask the students to solve the following questions.
Follow up
- Ask the students to solve the questions given in the textbook.
