# Addition of Units of Mass/Weight

## Students` Learning Outcomes

• Add measures of mass/weight in same units with and without carrying.
• Solve real life problems involving same units of mass/weight for addition with and without carrying.

### Information for Teachers

• In the addition of weights, grams are added into grams and kilograms into kilograms.

• If the addition of grams exceeds 1000 then the number of kilograms so obtained is added into kilograms, e.g. 850g + 175g = 1025g = 1kg + 25g.

• Question should be written vertically under column headings (g and kg).
• Sign of addition “+” should not be written under any column heading.

• While teaching the lesson, the teacher should also consult textbook at all the steps where and when applicable.

### Material / Resources

Writing board, chalk/marker, duster, paper strips, rippers of some objects (soap, tooth paste etc.) balance, weights

### Introduction

• Show the bath soap and tooth paste to the students and ask;

• What is the weight of tooth paste and bath soap?
• What is the weight of bath soap?
• What is total weight of both things?

### Development

Activity 1

• Write the following statement on board.

• Ask one of the students to write the units of weight on board.
• Ask another student to write the weights of basket of apples under the headings of units.
• Now tell them to find the total weight by adding grams into grams and kilograms into kilograms.

• 500g + 750g = 1250g = 1kg 250g
• Write 250g below g and carry 1 kg into kilograms column.
• 10kg + 12kg = 23kg, write it below kg column.

Activity 2

• Ask students to solve the following sums in their notebooks.

• Tell them firstly add grams into grams.
• Tell them if the numbers of grams exceeds 1000, the number of kilograms so obtained is added into kilograms. 1000g = 1kg
• Observe their work and guide them where necessary.
• Revise the relation between “g” and “kg” by asking from students.

Activity 3

• Ahmed` s weight is 35kg 450g and his sister`s weight is 30kg 780g, what is the total weight of both of them?
• Ask from students:
• What is Ahmad1s weight? (Expected answer; 35kg 450g)
• What is his sister’s weight? (Expected answer; 30kg 780g)
• Which operation can be used to find the total weight? (Expected answer; Addition)
• Ask one student to solve this question on board.

• Since 1250g = 1kg + 250g so total weight = 35kg + 30kg + 1kg + 250g + 666kg 250g.

### Sum up / Conclusion

• Conclude that;
• In the addition of weights, “g” is added into “g” and “kg” into “kg”.
• If the grams are 1000 or more than 1000, we carry the kilograms so obtained into the kilograms.

### Assessment

• Can we add kg into g?