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:

 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)

Development
Activity 1
 Write the following statement on the board.
 Ask following questions from the students and write their answers on board.

 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)

 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:

 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.

Assessment
 Ask the students to solve the following questions.
Follow up
 Ask the students to solve the questions given in the textbook.