Math 2 Lesson: One quarter

### 1.1. Knowledge to remember

Understand the concept of \(\frac{1}{4}\), recognize the image and spelling of “a quarter”.

### 1.2. Math forms

**Type 1: Check if a shape has been colored \(\frac{1}{4}\) shape or not.**

The figure is divided into 4 equal parts.

– Color 1 out of 4 parts.

If the picture meets the above two conditions, then it has been colored 1/4 of the picture.

**Form 2: Find \(\frac{1}{4}\) given number of squares.**

– Count the total number of squares

– Take the total number of cells divided by 4 to find \(\frac{1}{4}\) of the number of squares.

**Form 3: Practice the 4 bảng division table**

Repeat the 4 division table you have learned to find the value of the previous division.

### 1.3. Textbook Exercises Page 119

**Lesson 1**

Which shape has been colored \(\displaystyle{1 \over 4}\)?

__Solution method__

Find which shape is divided into four equal parts and has a colored part.

__Solution guide__

Colored \(\displaystyle{1 \over 4}\) image A, image B, image C.

**Lesson 2**

Which shape has \(\displaystyle{1 \over 4}\) the number of colored squares?

__Solution method__

– Step 1: Count the number of squares in the picture.

– Step 2: Find \(\dfrac{1}{4}\) the number of squares in each picture by dividing the number you just counted by \(4\).

– Step 3: Count the number of colored squares, if it is equal to the number found in step two, the figure has \(\dfrac{1}{4}\) the number of colored squares.

__Solution guide__

**Picture A: **There are \(8\) squares.

We have: \(8:4=2\) whose square \(2\) has colored squares.

So figure A already has \(\dfrac{1}{4}\) the number of colored squares.

**Figure B: **There are \(12\) squares.

Yes: \(12:4=3\) and in the picture there are \(3\) colored squares.

So figure B already has \(\dfrac{1}{4}\) the number of colored squares.

**Figure C:** There are \(16\) squares.

We have: \(16:4=4\) and in the picture there are 8 colored squares.

So figure C does not have \(\dfrac{1}{4}\) the number of colored squares.

**Figure D:** There are \(16\) squares.

We have: \(16:4=4\) and in the picture there are 4 colored squares.

So figure D has \(\displaystyle {1 \over 4}\) the number of colored squares.

**Conclude:** Picture A; B; D are colored shapes \(\displaystyle {1 \over 4}\) number of squares

lesson 3

Which figure has circled \(\displaystyle{1 \over 4}\) the number of rabbits:

__Solution method__

– Count the number of rabbits in the picture and then find \(\dfrac{1}{4}\) of that number.

– Count the number of circled rabbits, if equal to the value found in the previous step, the figure has circled in \(\dfrac{1}{4}\) the number of rabbits.

__Solution guide__

In both pictures there are \(8\) rabbits.

We have: \(8:4=2\)

That figure A has \(2\) circled rabbit; Figure B has \(4\) circled rabbit.

So figure A has circled \(\displaystyle {1 \over 4}\) the number of rabbits.

### 1.4. Solving Textbook Exercises page 120

**Lesson 1**

Mental arithmetic:

8 : 4 = 12 : 4 = 20 : 4 = 28 : 4 =

36 : 4 = 24 : 4 = 40 : 4 = 32 : 4 =

__Solution method__

Review the learned division table by 4 and fill in the blanks with the results.

__Solution guide__

8 : 4 = 2 12 : 4 = 3 20 : 4 = 5 28 : 4 = 7

36 : 4 = 9 24 : 4 = 6 40 : 4 = 10 32 : 4 = 8

**Lesson 2**

Mental arithmetic:

4 x 3 = 4 x 2 = 4 x 1 = 4 x 4 =

12 : 4 = 8 : 4 = 4 : 4 = 16 : 4 =

12 : 3 = 8 : 2 = 4 : 1 =

__Solution method__

Calculate the value of the multiplication and then enter the value of the two related division operations.

__Solution guide__

4 x 3 = 12 4 x 2 = 8 4 x 1 = 4 4 x 4 = 16

12 : 4 = 3 8 : 4 = 2 4 : 4 = 1 16 : 4 = 4

12 : 3 = 4 8 : 2 = 4 4 : 1 = 4

**lesson 3**

There are 40 students divided equally into 4 groups. How many students are there in each group?

__Solution method__

To find the solution, divide the number of students by the number of groups.

__Solution guide__

The number of students in each group is:

40 : 4 = 10 (student)

Answer: 10 students.

**Lesson 4**

There are 12 guests who need to cross the river, each boat carrying 4 guests (excluding the boatman). How many boats are needed to carry all those passengers?

__Solution method__

To find the solution, we divide the number of guests by 4.

__Solution guide__

Number of boats required is:

12 : 4 = 3 (boat)

Answer: 3 boats.

**Lesson 5**

Which figure has circled \(\displaystyle {1 \over 4}\) the number of deer:

__Solution method__

– Count the number of giraffes in each picture and divide by 4.

– Choose the picture with the number of giraffes circled by the result of the division just found.

__Solution guide__

Figures a and b have 8 giraffes.

Which 8: 4 = 2.

So figure a has \(\displaystyle {1 \over 4}\) the number of deer circled.

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