Math 2 Lesson: Kilogram

### 1.1. Knowledge to remember

### 1.2. Math forms

**Type 1: Read and write mass units.**

The unit “kg” is read as “Ki – Lo – Gram”.

– How to read: Read the number and then pair it with the reading of the unit name as “kilogram”

– How to write: Write the number and pair it with the unit symbol “kg”

**Form 2: Perform calculations with units of mass**

– I do math with numbers.

– Keep the unit of measurement in the result.

**Note: **The figures in a calculation should be in the same unit of measure.

**Form 3: Math Quiz**

– Read and analyze the problem carefully, identify known and unknown numbers.

– Find a way to solve the problem, pay attention to the solution of the “more” form of math; “less” just learned.

– Present the lesson and check the results just found.

### 1.3. Solving Textbook Exercises page 32

**Lesson 1**

Reading and writing (according to the form):

__Solution method__

– Applying knowledge: Kilogram is abbreviated as kg.

– The mass of the pumpkin is equal to the sum of the two weights.

– Write the reading and writing of the volumes.

__Solution guide__

**Lesson 2**

Sample calculation:

1kg + 2kg = 3kg 10kg – 5kg =

6kg + 20kg = 24kg – 13kg =

47kg + 12kg = 35kg – 25kg =

__Solution method__

Sum the two numbers and then write the unit “kg” after the result you just found.

__Solution guide__

1kg + 2kg = 3kg 10kg – 5kg = 5kg

6kg + 20kg = 26kg 24kg – 13kg = 11kg

47kg + 12kg = 59kg 35kg – 25kg = 10kg.

**lesson 3**

The big bag of rice weighs 25kg, the small bag of rice weighs 10kg. How many kilograms do both bags of rice weigh?

__Solution method__

**Summary**

Big bag of rice: 25kg

Small bag of rice: 10kg

Both: ….kg?

**The answer**

To find the solution, we take the mass of the large bag of rice plus the weight of the small bag of rice.

__Solution guide__

Both bags weigh in kilograms:

25 + 10 = 35 (kg)

Answer: 35kg

### 1.4. Textbook Exercises Page 33

**Lesson 1**

a) How many kilograms does the orange bag weigh?

b) How much does Hoa weigh?

__Solution method__

Read the weight of the bag of oranges and Hoa on each picture.

Note: Kg is read as kilogram.

__Solution guide__

a) A bag of oranges weighing 1kg.

b) Hoa’s weight is 25kg.

Lesson 2

Which sentence is correct? Which sentence is wrong?

a) The orange weighs more than 1kg.

b) Oranges are lighter than 1kg.

c) The grapefruit weighs more than 1kg.

d) Grapefruit is lighter than 1kg.

e) An orange is heavier than a grapefruit.

g) A grapefruit is heavier than an orange.

__Solution method__

– Observe the image of the weighing plate, the position of the needle.

– Read the sentences and then fill in True or False as appropriate.

__Solution guide__

Sentence a) is wrong

Sentence b) is correct

Sentence c) is correct

Sentence d) is wrong

Sentence e) is wrong

Sentence g) is correct

**lesson 3**

Calculate:

3kg + 6kg – 4kg = 8kg – 4kg + 9kg =

15kg – 10kg + 7kg = 16kg + 2kg – 5kg =

__Solution method__

Perform the calculation with the numbers in order from left to right and then write the unit “kg” after the result you just found.

__Solution guide__

3kg + 6kg – 4kg = 5kg 8kg – 4kg + 9kg = 13kg

15kg – 10kg + 7kg = 12kg 16kg + 2kg – 5kg = 13kg

**Lesson 4**

Mom bought 26kg of both glutinous rice and plain rice, including 16kg of plain rice. How many kilograms of sticky rice did mom buy?

__Solution method__

To find the number of kilograms of glutinous rice my mother bought, we subtract 26kg from the weight of the sticky rice.

__Solution guide__

The number of kilograms of glutinous rice she bought is:

26 – 16 = 10 (kg)

Answer: 10kg.

**Lesson 5**

The chicken weighs 2kg, the goose weighs 3kg more than the chicken. How many kilograms does the goose weigh?

__Solution method__

To find out how many kilograms a goose weighs, we take the weight of the chicken plus 3 kg.

__Solution guide__

The goose weight in kilograms is:

2 + 3 = 5 (kg)

Answer: 5kg.

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