Lesson Planning of Addition and Subtraction of Units of Mass / weight
Subject Mathematics
Grade 4^{th}
Students` Learning Outcomes
 Add and subtract expressions involving similar units.
 Use appropriate units to measure weight of different objects.
 Solve real life problems with application of above two.
Information for Teachers
 Kilograms and grams are used to measure the weight of different objects.
 Kilograms are used to measure heavy objects whereas grams are used for lighter objects.
 Similar units can be added or subtracted only, if units are not similar, we make them similar before addition or subtraction.
 For adding grams into kilograms first we convert kilograms into grams and for this we multiply number of kilograms by 1000.
 During this lesson, the teacher should consult textbook at each level wherein and whenever it is required.
Material / Resources
Writing board, chalk/marker, duster, school bag, scale, pictures of almond, peanut, flour, rice, sugar and salt, textbook
Introduction
 Collect various objects that are easily available, as; toys, school bags, geometry box etc.
 Place the objects on a table along with a set of simple balances.
 Weigh these objects on balance and write on the board. “The geometry is lighter than school bag”.
 Put some more object on the geometry side and tell the students that now weight of both sides look same.
 Ask the students what do you think would be the weight of all toys.
 Take their feedback and tell them that it would be in kilograms
 Tell them that today we will learn about the application of “units of weight”.
Development
Activity 1 Addition of the same units:

Activity 2
Or

Activity 3
i) 75 kg, 888 g + 170 kg, 501 g = ____________? ii) 90 kg, 400 g + 11 kg, 905 g = ____________? iii) 178 kg, 388 g – 59 kg, 430 g = ____________? iv) 32 kg, 332 g – 14 kg, 581 g = ____________?

Sum up / Conclusion
 Finish this lesson by asking different students to repeat the key concepts that we have learnt today, as; 1 kg = 1000 g
 Kilograms are used to measure heavy objects, whereas grams are used for lighter objects
 Similar units can be added or subtracted only, if units are not similar, we make them similar before addition or subtraction.
 We multiply kg by 1000 to convert kg to g and divide g by 1000 to get kg.
 If expressions involve mix units like kg & g both, we write kg below kg and g below the g and then we add or subtract.
Assessment
 Now assign different questions to the students to assess whether they have got your points or not.
 Take weight of your friend and his /her school bag and find difference which one is heavier, as;
 Ali`s weight is 25 kg and 320 g whereas his bag`s weight is 5 kg and 20 g. which one is heavier and how much?
 Subtract 25 kg, 320 g – 5 kg, 20 g = __________?
Follow up
 Fill in the following table with the help of family members and write amounts of items given below used in a month and then add all the quantities: as ;