Mathematics

7.1 The Kilogram as the standard unit of mass

Activity 7.1

We measure mass in kilograms (Kg).

Give another way of measuring mass.

7.2 Balances and their types

Activity 7.2

7.3 Measuring masses of objects in Kg

Activity 7.3.1

Activity 7.3.2

Do the same and read the mass of different objects in Kilograms and record masses on a balance.

Activity 7.3.3

Activity 7.3.4

7.4 Importance of Kilogram (Kg)

Activity 7.4.1

7.4.1Activity 7.4.2

Activity 7.4.3

7.5 Comparing masses of objects

Activity 7.5.1

Activity 7.5.2

Activity 7.5.3

Activity 7.5.4

Activity 7.5.5

7.6 Addition of masses in kilogram

Activity 7. 6

Example:   205 kg + 414 kg =

7.7 Word problems involving the addition of mass measurements

Activity 7. 7

Look at the worked out example below:

Example:

I weigh 32Kg; my brother weighs 46Kg. Find our total weight?

Solution:

Solve the following problems:

1.    Last month Kamanzi kept 12Kg of cassava in the store.

        His brother kept15 Kg of cassava. How much cassava did they save altogether?

2.    One day, Rukundo sold 50Kg of rice in the morning. In the afternoon, he sold 25Kg of rice. 

        How much rice did Rukundo sell on the same day?

3.     At home we cook 5Kg of bananas in the morning. In the evening we cooked 4 Kg of bananas. 

         Find the mass of bananas we cook per day.

4.     Every day Mbabazi sells 15Kg of sugar and 25Kg of sorghum flour. Find the total number of Kg Mbabazi sells

         per day.

7.8 Subtraction of units of mass in Kg

Activity 7. 8

Example: 475 kg - 364 kg =

7.9 Word problems on the subtraction of units of mass

Activity 7. 9

Study the worked out example below:

Example:

I poured 28Kg of rice in a sack that requires 59 Kg to be filled. How many Kg are needed to fill the sack?

Solution:

Solve the following problems:

1.    A businessman had 150Kg of beans. He sold 75 Kg from them. 

        How many kilograms of beans did he remain with?

2.     Gisa harvested 247Kg of rice. He gave his neighbors 130 Kg of rice. 

           How many kilogram of rice did he remain with?

7.10 Multiplication of mass measurements by a whole number

Activity 7. 10

Example: 82 kg x 4 =

7.11 Word problems involving multiplication of mass measurements by a whole number

Activity 7. 11

Study the example below:

Example:

My parents harvested 6 sacks of beans. Each sack weighs 71Kg. How many kilograms of beans did my they harvest?

Solution:

Solve the following problems:

1)      At home we cook 6 Kg of potatoes. How much potatoes do we cook in 3 days?

2)       Mugabo carries 61 Kg of bananas on the wheelbarrow. How many kilograms will he have if he caries bananas 3 times?

3)       When preparing breads, Muhizi uses 31Kg of millet flour per day. How many kilogram of millet flour will he use in 10 days?

7.12 Division of mass measurements by a whole number

Activity 7. 12

7.13 Word problems involving the division of mass mea-surements by a whole number

Activity 7. 13

Discuss the example below:

Example:

Solve the following problems:

1.     Share 450 Kg of rice equally among 5 people. How many kilograms will each person get?

2.     Four people bought 328 Kg of sugar to be shared equally among them. Find the share for each person?

3.     There are 284 Kg of beans to be shared equally in 4 sacks. What is the mass for each sack?

4.     During the harvesting of beans, a mother got 48Kg. She equally shared this harvest among 4 children. 

         What was the share of each child?

5.   At home we use 30Kg of potatoes in 5 days. How many kilograms of potatoes do we use in one day?

END UNIT ASSESSMENT 7

1. Comment by Yes or No

      (a) Kg is the standard unit of mass measurements........

      (b) Kg is used to measure the capacity of objects……

2.  Give 3 types of balances.

3. Use <, > or = to compare masses =

4. Arrange the mass measurements for objects from the lightest to the heaviest mass

           478 kg,     874 kg,      487 kg,      784 kg,      847 kg,      748 kg

5. Arrange the mass measurements for objects from the heaviest to the lightest mass

                   836 kg,      368 kg,     638 kg,     863 kg,      386 kg,      683 kg

6. Find the answer

7. Solve word problems

    (a) Abatoni bought 6 sacks of cement. If one sack weighs 50Kg, Find the number of Kg she bought. 

    (b) During the beginning of season B of Agriculture, Rwema shared 85Kg equally to his 5 children. 

     Find the quantity for each child.

        (c) In the first season of farming we got a harvest of  356 kg  of rice. 

        In the second season we got  278 Kg  and we got  319 Kg  in the third season. 

        Find the total harvest we got in these three seasons. 

       (d) The store of our school had  895Kg  of beans. 

        If the school used  547 Kg of beans for students’ meal, find the quantity of beans which remained in the store.

       (e) Last year I got  21Kg  of rice as a harvest. In this year I got  185 Kg  of rice. 

         Find my total harvest for these two years. 

         (f) Share  472 Kg  of sugar equally to 4 families; How much sugar will each family get? 

         (g) Kamana weighs  45Kg. His sister weighs  55Kg. Find the total weight for Kamana and his sister.