Lesson Plan of Subtraction of Units of Mass/Weight
Subject Mathematics
Grade III
Students` Learning Outcomes
 Subtract measures of mass/weight in same units with and without borrowing.
 Solve real life problems involving same units of mass/weight for subtraction with and without borrowing.
Information for Teachers
 Write the values vertically under column headings (g and kg)
 Large value in upper row and small value in bottom row.
 To find the difference of weights, grams are subtracted from grams and kilograms from kilograms.
 If the grams column has a smaller number on top, the numbers on top borrows from the number to its left then adds into it, then find the difference. 1kg = 1000g
 Repeat the key words for subtraction, how much left, reduced, lighter, heavier, how much etc.
 While teaching the lesson, also consult textbook where and when applicable.
Material / Resources
Writing board, chalk/marker, duster, pointer/stick, balance, weights and weight textbook
Introduction
 Ask from students;

 A bar of chocolate weighs 100g. Abu eats 40g. How much is left?



 In May, Sameer weighed 52kg. In June, his weight had reduced to 48kg. How much weight did he lose?

Development
Activity 1
 Write the statement on board.
 At a construction site there was 350kg 950g of sand. If there are 49kg 375g of sand is used in a material. How much sand is left?
 Ask the following questions to the students:

 What was the total weight of sand? (350kg950g)
 How much sand was used in material? 49kg375g)
 How we find the remaining weight of sand? (by construction)

 Write their response on the board.
 Ask them to solve it.
 Subtract grams from grams, as such; 950g – 378g = 675g.
 Now subtract “kg” from “kg”, as such; 350kg – 49kg = 301kg, hence, the remaining weight of sand is 301kg675g.
 Write another statement on the board.
 Ask the following questions to the students.
 What was Ali`s weight with shoes? (45kg15g)
 What was the weight of shoes? (1kg150g)
 Which operation will we use to find the actual weight of Ali?(Subtraction)
 Write their responses on board under the heading of units(kg and g)
 Ask one student to solve it on the board.
 Ask them how we subtract 150g from 15g? (we borrow 1kg from 5kg)
 How many grams are there in 1kg?(1000g)
 Now how many grams we have? (1018g)
 Hence, actual weight of Ali is 43kg 868g.
Activity 2
 Ask students to solve the following sums in their notebook.
 Tell them, firstly subtract grams from grams.
 Tell them, if the grams column has a smaller number on top, the numbers on top borrows from the number to its left then adds into it, then find the difference. 1kg = 1000g
 Observe their work and guide them where necessary.
 Revise the relation between “g” and “kg” by asking from the students.
Sum up / Conclusion
 Conclude that:

 To find the difference of weights, grams are subtracted from grams and kilograms from kilograms.
 If the grams column has a smaller number on top, the numbers on top borrows from the number to its left then adds into it, then find the difference. 1kg =1000g

Assessment
 Ask the following questions to the students;

 Which is the smaller unit of weight?
 Which unit is used to weigh heavier objects?
 Which mathematics operation is performed for finding the difference between the weights of two objects?

Follow up
 Ask students to find the difference of weight of any two daily grocery items, like; rice 2kg 500g, red chili 250gm etc.
 Ask the students to solve the questions given in the textbook.