LỚP 2: PHẦN LỜI BÀI 1-10

BÀI 1

1,Have you ever heard of origami Starry?

2.No, origami is an art form of Japan where different objects and shapes are made using paper folding technique. .

3.You must be wondering why I’m asking you about origami.

4.Today we are going to use paper folding to learn a new topic in math.

5.See Starry, let’s take this round paper and fold it in such a way that we divide it into to equal parts. 

6.Now, let’s open the fold. We see a horizontal mark passing through the center. 

7.Let’s mark it with pencil. In how many part is the circle divided Starry? 

8.Yes, the circle has been divided into 2 equal parts. 

9.Now Starry, we shall colour 1 part of this circle red. 

10.So now we can say that one part out of two equal parts is coloured red. 

                                                    

It can also be written as 1 over 2(1/2): 

One over two or haft is known as a fraction. 

So Starry, a fraction is a part of the whole. 

Now observe the folds made in this rectangular sheet. 

The rectangular sheet is divided in three equal parts. 

Let’s draw lines on the folds made. 

How many parts should we color? Ok, let’s color only one part. 

So we can say that one out of three parts are coloured. 

In the form of a fraction it can be written as 1 upon 3. 

Should we fold this square shape sheet now? 

OK. Here it is. How many equals part are formed? 
Yes, 4. Uh, Let’s colour 3 parts in this sheet. So we say that 3 parts out of 4 are coloured. Vâng, 4. 

Can you write the fraction of the coloured part? 

Yes, the fraction is 3 upon 4.

Starry, look at the picture of this cake. Into how many pieces in this cake cut? 

Yes, 8 equal pieces 

Now, support I eat 3 pieces of this cake. What part of the cake do I eat? 

Yes, 3 pieces out of 8 pieces means I eat 3 upon 8 parts of the cake. 

Look at the next picture Starry. 

Here the circle has been devided into 8 equal parts. 3 parts are coloured blue, 4 parts red and 1 part yellow. 

Can you tell me the fraction representing the blue coloured part.

Yes, 3 upon 8 parts are coloured blue. We can also write as 4 upon 8 part is coloured red. And 1 upon 8 part is coloured yellow. 

Starry, I know you like colouring. So let do an activity where we revise about fraction and also colour.

See, we have a few shapes cut out on a white paper. These shapes have also been devided into parts. 

We have to colour the part of the figure that is indicated by the fraction.

Let’s state the first shape. What fraction is mentioned here? 

Yes. 1 upon 2, so we shall colour 1 part out of the 2 parts. 

Now, consider the second shape. The fraction is 3 upon 4. That means it has been devided into 4 equal parts. How many parts shall we colour? Yes, 3 parts. 

In the next shape the fraction mentioned is 5 upon 7 , so we shall colour 5 parts out of the total 7 parts. Look at the last shape Starry, and how many parts have been devided ? 

Yes, 12. The fraction for the coloured part is 7 upon 12.  So how many parts shall we coloured? 

Yes, 7 parts.  .

BÀI 2

Hello Starry, let us revise fraction.  

This square is divided into 2 equal parts.  

Out of which one is coloured. 

So, we say that haft the square is coloured.  

So the coloured part shows the fraction 1upon 2 that is haft. 

This figure is divided into 4 equal parts. 

 Out of which one part is coloured. .

So the coloured part shows the fraction 1 upon 4 or 1 fourth or a quarter.  

Now, look at this circle. It has been divided into 4 equal parts. 

Out of which 3 parts are coloured.  

So the fraction shows by the coloured part is 3 upon 4 or 3 fourths or 3 quarter. 

But Starry, are you aware of other fractions.   

Alright. Let us see some more fractions. 

Look at this cake. Let us divide it into 3 equal parts.  

Now, we put icing on one of the parts.  

So we have put icing on one part out of 3 parts.  

This part shows the fraction 1 upon 3 or 1 third. 

Now look at the part without the icing. There are 2 parts without the icing. 

So, they show the fraction 2 upon 3 or 2 thirds. 

Now look at this figure. It has been divided in to five equal parts. Bây giờ nhìn vào hình  này. 

Let us coloured any 2 parts. 

The coloured part shows the fraction 2 out of 5 or 2 fifths.  

The uncoloured part shows the fraction 3 upon 5 or 3 fifths.  

Look at this strip of paper the number of equal parts it is divided into are 7.  

Number of part coloured is 4 .  

So the fraction showed by coloured paper is 4 upon 7.  

The fraction showed by uncoloured paper is 3 out of 7. 

Hey Starry, look at these fractions. 

The meaning of the first fraction is out of 11 equal parts 7 are selected. 

 So the numerator is 7 and the denominator is 11.  

We read the fraction as 7 upon 11.  

Let us look at the second fraction. 

It means out of 9 equal parts 2 are selected.  

Here 2 is the numerator and 9 is the denominator. 

We read as fraction as 2 upon 9. 

See what the third fraction means. 

 It means out of 13 equals parts 5 are selected. 

So the numerator is 5 and the denominator is 13.  

We read the fraction as 5 upon 13.  

Let us now revise what we have learnt. Fill in the blanks.  

On the first fraction the numerator 5 and the denominator is 8.

The fraction is read as 5 upon 8. 

On the second fraction. The numberator is 2 and the denominator is 11.

So we write the fraction as 2 upon 11. We also read the fraction as 2 upon 11.  

It means out of 11 equal parts 2 are selected. 

This fraction is read as 3 upon 7.  

So we write the numerator as 3 and the denominator as 7. 

We write the fraction as 3 upon 7.  

It means out of 7 equal parts 3 are selected.  

The next fraction means out of 6 equal part 1 is selected.  

So the numerator is 1 and the denominator is 6. This fraction is read that 1 upon 6.  

So now you have learn some more fractions.I’m sure you must enjoy this. Bye.

BÀI 3

Another explanation for fractions.  

Hi Starry, let revise fractions.  

Look at this fraction, here out of 3 equal parts 2 are selected.  

So 2 is a numerator and 3 is denominator.  

We read this fraction as 2 upon 3. 

Now Starry, look at these paper strip.  

This figure is divided into 3 equal parts.  

Each part of the 3 equal parts of the whole is 1 upon 3.  

So 2 such part is 2 upon 3.  

So the coloured part is 2 upon 3 and the uncoloured part is 1 upon 3.

Let us look at another example.  

Here 1 whole is divided into 5 equal parts.  

So each part equal 1 upon 5. Here 3 such part is 3 upon 5.  

So the part with design is 3 upon 5 and the part without design is 2 upon 5. 

Isn’t it interesting Starry?  

Now observe this.  

One whole is divided into 4 parts. 

Each coloured part is 1 upon 4. 3 such part equal 3 upon 4.  

Look at this one, if each part is 1 upon 11, 5 such part is 5 upon 11.  

Look at the next one, if each part is 1upon 13, 6 such part is 6 upon 13.  

If each part is 1 upon 7, then the four such parts will be 4 upon 7. 

Let us revise. Fill the boxes with the proper fraction.   

The first one state each part equal 1 upon 3, 2 such parts is (dash). The answer is 2 upon 3.  

The second one state that each part is 1 upon 9, 7 such parts is (dash). The answer is 7 upon 9.

The next one tells us that it part equal 1 upon 8, so 5 such parts equal (dash). The answer is 5 upon 8.  

Let us do another activity for each fraction. 

Name the numerator and denominator. Write the fractions in words.                                              

Answer the first one. 

Here the numerator is 3 and denominator is 13 and the fraction is read as three upon thirteen.  

Answer the second one here the numerator is 7 and denominator is 9 and the fraction is read as seven upon nine.   

Answer the third one.   

Here the numerator is 5 and the denominator is 21 and the fraction is read as five upon twenty-one.  

And now answer the last one. 

Here the numerator is 6 and denominator is 7, the fraction is read as six upon seven.  

So, today you have learnt another way of looking at the fractions.  

BÀI 4

What shape is it?  

It’s a circle.  

What shape is it? It’s a triangle. 

What shape is it? It’s a square. 

What shape is it? It’s a rectangle. 

What shape is it? It’s a semicircle.

What shape is it? It’s an oval. 

What shape is it? It’s an ellipse. 

What shape is it? It’s a trapezoid. 

What shape is it? It’s a parallelogram.

What shape is it? It’s a rhombus.              

What shape is it? It’s a kite.

What shape is it? It’s a pentagon.

What shape is it? It’s a hexagon.

What shape is it? It’s a heptagon.

What shape is it? It’s an octagon.

What shape is it? It’s a nonagon.

What shape is it? It’s a decagon.

What shape is it? It’s a star.

What shape is it? It’s a crescent.

What shape is it? It’s a cross.

What shape is it? It’s a heart.

Come on shapes!

Bye bye!

BÀI 5

Starry,see

I have got some colourful marble papers.

Let us make some nice craft items from these.

Now, let us make a bus.

First, take one paper fold this into 2 hafts.

Now stick this on another sheet of white paper.

Draw 2 wheels below the body of the bus. You did not understand. Ok.

I will show you once again.

Take a marble paper and fold this into 2 parts like this.

See Starry, if you unfold the paper we see a horizontal line.

Now fold it and take a fold this paper on another sheet of white paper.

No no Starry. You should not stick it like this.

See now, if you unfold the paper. We see a vertical line.

We have to stick it in such a way that horizontal forward is seen.

Do you understand Starry? Ok.

Then you practice this later.

Let me show you something interesting now.

Let’s take a sheet of marble paper. Fold the paper this width.

Now I fold it. The line that we see here is called the horizontal line.

Now take the paper and fold it in this way.

The line that you see now is called the vertical line.

Now fold the paper like this.

I’m unfolding it, we see a line which is not horizontal nor vertical is just called a slanting line.

Starry see! I have also got satin ribbon with me.

Now I am going to hold this satin ribbon in my hand and stretch.

If I stretch the ribbon and hold it like this. Which line is formed?

Yes, the horizontal line.

Now see the vertical line is formed.

What about this one Starry?

Yes, it is a slanting line.

Now Starry, let us learn to draw these line on the paper.

Uhm… see we have got here a compass box and eraser and the book.

Using these let us draw the line, first we show you the compass box.

Take the compass box and keep it on the paper.

Here let us first draw horizontal line.

Now keep the compass like this. And draw the vertical line.

Now turn the compass like this and draw the slanting line.

Similarly we can also draw lines using this eraser and a book.

You can try it later Starry!

What happens Starry? What are you looking for?

Oh.. This is a scale.

Shall we see how a line is drawn using a scale?

Which line is drawn here Starry? Yes, a vertical line.

The next one is the horizontal line. And now let’s draw the slanting line.

Starry, I have one interesting activity for you now.

Here is a grid of squares. On it a nice drawing has been done.

We have another grid of empty squares.

Let’s observe the drawing and draw the same figure using a scale and a pencil.

See Starry, we have drawn vertical line, horizontal line and slanting line in this figure.

Starry, you try and draw such a figure using a scale and pencil.

Starry! Look what I have here?

There is a rubik’s cube, a match box, a bangle and a paper weight.

We shall lay these objects on the paper.

Let us now trace their edges with the pencil.

The shape is formed by tracing the edges of the rubik cube is a square.

The shape is formed by tracing the edges of the match box is a rectangle.

What shape is formed by tracing a bangle Starry?

Yes, around shape. It is also call a circle.

The paper weight forms the shape of the triangle.

Starry, the shapes are drawn here. Now name them correctly.

Yes, the first shape is a triangle.

The second one is a square.

The third shape is a circle.

The last one is a rectangle.

Match the shape in column A with their names in column B.

Which is the first shape Starry? Yes, it is a rectangle.

The second shape is a circle.

The third one looks a little different, can you identify this shape?

Yes, it is a triangle.

The last shape is a square.

Starry, can you name some articles with all of these shapes.

Yes, a coin has the shape of the circle also the ciabatta

A black board is square in shape.

The scale is rectangular in shape.

Starry look around for different articles and observe their shapes.

BÀI 6

Party caps, balloons, masks, whistles, candles.

What’s happening Starry?

Is there a party on? Oh, there is.

But everything’s seen to be divided into 2 groups.

Starry here are the party caps.

In this group, there are 1-2-3-4-5, 5 caps. We write the number 5.

And here are 1-2-3 caps, we write the number 3.

Now Starry, which group has more caps? Right, the group with 5 caps in it.

So we say 5 is the bigger of the 2 numbers and 3 is the smaller of the 2 numbers.

Look at these colourful balloons.

In one group we have 1-2, 2 balloons. We write 2.

In the other we have 1-2-3-4-5-6-7, 7 balloons. We write 7.

                 

Since the group with 7 balloons has more balloons it is the bigger number and 2 is smaller number.

Have you understood Starry?

And now the whistles.1-2-3-4-5-6-7-8 whistles. We write 8.

1-2-3-4, 4 whistles. We write 4.

8 is the bigger number and 4 is the smaller number.

Are these masks Starry? Let’s count them.

1-2-3-4-5-6-7, 7 masks. We write 7.

1-2-3-4-5-6-7-8, 8 masks. We write 8.

Which do you think is the bigger number Starry?

Right, 8 is the bigger number and 7 is the smaller number.

Shall we now do an activity together!

Which of the two is the bigger and which is the smaller number?

Let us count the number and find out.

Cupcakes:

1-2-3, 3 cupcakes.

1-2-3-4-5-6, 6 cupcakes.

The bigger number is 6 and the smaller number is 3.

Ice cream:

1-2-3-4-5, 5 ice creams

1-2, 2 ice creams

The bigger number is 5, the smaller number is 2.

And now some pizzas:

1-2-3-4, 4 pizzas.

1-2-3-4-5-6-7, 7 pizzas.

7 is the bigger number and 4 is the smaller number.

Samosas: 

1-2, 2 samosas

1-2-3-4-5, 5 samosas

5 is the bigger number and 2 is the smaller number.

And now Starry, all you have to do is circle the bigger number.

9 and 3, the bigger number is 9.

7 and 10, the bigger number is 10

3 and 8, the bigger number is 8.

2 and 3, the bigger number is 3.

4 and 1, the bigger number is 4.

That was very good Starry!

Starry, today at the party you have learnt how to find the bigger and smaller of two given numbers.

BÀI 7

Starry, can you read the number shown here.

Yes, the number is seventy-two.

Let us see what happens if we change the position of the digits.

Now the number is twenty-seven.

Observe carefully Starry, in both these numbers we have used the same digits.

But the places of the digits is different.

hens the value of the digits is also changed.

For example, consider the number 72.

The digit 7 shows the number of tens.

               

So, its place value is 7 tens that is seventy.

In which place in the digit 2 Starry?

Yes, the digit 2 shows the number of ones.

Hens the place value of 2 is 2 ones that is 2.

Let us take a look at the next number 27.

Here what does digit 2 show?

Yes, the digit 2 shows the number of tens. So its place value is 2 tens that is 20.

What about the digit 7 Starry?

Yes, digit 7 shows the number of ones. So its place value is 7 ones that is 7.

Have you understood Starry? Ok.

And let us write the place values of the digits in the given numbers!

Let’s see the number 36.

What does the digit 3 show?

Yes, the digit 3 shows 3 tens. So its place value is 30.

The place value of 6 is 6.

Since, it shows 6 ones.

Hey Starry, see in 44. Both of the digits are 4.

We place have same place values are different.

You are right Starry! Both the 4 we have different place values.

The 4 in the tens place has placed value 40.

The 4 in the ones place has placed value 4.

Look at the next number 93.

Can you tell me the place value of 9, Starry?

Yes,9 shows the number of tens. So its place value is 90.

The place value of 3 is 3 ones. That is 3.

Starry, do you know the sum of the place values of the digit of a number is equal to the number itself.

Look at this example consider the number 48.

Can you tell me the place value of the digit.

Yes,4 is the tens place digit. So its place value is 40.

8 is the ones place digit. So its place value 8.

Sum of the place value: 40 plus 8 that is 48

Starry, now can you write the number 62 as the sum of the place values of it digits?

Yes, in the number 62 the digit 6 is the tens place digit. So its place value is 60.

The digit 2 is the ones place digit. So its place value is 2.

Hens the number 62 is written as 60 plus 2.

Hey Starry, take a look at this abacus.

How many beads are there in the tens column.

Yes, there are 4 beads. So, we get 4 tens.

Can you tell which number is formed Starry?

Yes, 4 tens and 7 units means 40 plus 7 that is 47.

Let us show the next example Starry!

Fill in the blanks with correct digits.

Look at the first sentence.

The place value of 7 in the number 71 is that. Can you answer this?

Yes, 7 is in the ten place. So its place value is 70.

Let us write the next blank now.

If the tens place digit is 8 and the ones place digit is 3, then the number formed is that plus that, that is that.

What is the place value of 8 Starry?

8 is in the tens place. So its place value is 80.

The place value of 3 is 3, so the number formed is 80 plus 3 that is 83.

Now, the next one.

This is simple Starry! The place value of 1in 21 is that.

You seem excited, yes yes the answer is 1.

Let us fill in the last blank, in the number 30 the place value of 3 is that, the answer is 30.

So Starry, did you understand the value of a digit will depend up on the place it is written.

BÀI 8

Starry what I have here? Remember these numbers card?

Come on, let’s learn something new with these cards today.

First let place these card upside down so that we are not able to read the numbers on them.

Now here’s a table. Three columns have been drawn.

Here H stands for hundreds, T for tens, and U for units.

              

Ok. Now let’s start.

Let’s pick up any three cards and place them one by one in each column.

We place the number 5 in the hundreds column, the number 3 in the tens columns and the number 7 in the units column.

Can you read this number Starry?

Yes, this number is five hundred and thirty seven.

In what place is the number five? Yes, 5 is the hundreds place digit.  

So its place value is five hundreds or five hundred.

Can you tell me now the place value of 3.

That right,3 is the tens place digit. So its place value is 3 tens or 30.

And finally 7 is the units or one place digit.

So its place value is 7 ones or 7.

Wasn’t that interesting? Ok.

And let us learn the place value of some more three digit numbers.

Let us choose three more cards. Which digits do we get?

Ah… 8 is in the hundreds place, 6 is in the tens place and 4 is in the units place.

Now let us find out their place value.

What will be the place value of 8 Starry?

8 is in the hundreds place digit. So its place value is 8 hundred.

Place value of 6 is 60 as it is the tens place digit and place value of 4 is 4.

Now it’s time for the three digit number.

Here we have the hundred place has digit 9, then tens place has digit 6, and the units place has digit 2.

Now tell the place value of the digit Starry!

Hey Starry, wait!

We have not place the card in the tens place correctly, the digit in the tens place is 9 and not 6.

Here now tell place values! The place value of digit 9 in hundreds place is 900.

Will the place value of digit 9 in tens place be same?

No, here the place value of 9 is 90. The place value of digit 2 is 2.

So remember Starry, the place value of the digit changes depending upon its place in the given number.

Are you ready to solve some examples now Starry? Ok. Let’s start!

A group of numbers is given here.

We have to observe the numbers and answer the questions.

Let us read the first question.

We have to write the place value of the digit 4 in the number 421.

In which place is the digit 4? Yes, digit 4 is in the hundreds place.

So its place value is 400.

Starry, can you find any two numbers in which the place value of 8 is 80.

Yes, in the number 983 and 882, the place value of 8 is 80.

In the next question, we have to find the place value of 1 in the number 731.

Digit 1 in units place. So its place value is 1.

Hey Starry, this question is interesting!

We have to find the number in which digits in the units place and tens place have place value 0.

Can you answer this?

Yes, the correct answer is 300.

Let us solve the next example.

Pick the correct answer out of the given choices.

Let’s read the first statement.

The place value of the digit 6 in the number 365 is 60 or 600.   the correct answer is 60.

The place value of 9 in the number 912 is 90 or 900.

Yes, the correct answer is 900.

In the number the place value of the digit 8 is 800, the place value of the digit 7 is 70 and of 4 is 4.

So the number formed is 784 or 874.

Yes, the answer is 874.

So Starry, before finding place value of the digit in a number, It is important to identify its place in the number

BÀI 9

1 plus 1 equals 2

1 plus 2 equals 3.

1 plus 3 equals 4

1 plus 4 equals 5

1 plus 5 equals 6

1 plus 6 equals 7

1 plus 7 equals 8

1 plus 8 equals 9

BÀI 10

Starry, do you remember these number beads.

We use them to make a number line.

Let us put them together and make one again.

The first bead will be 0 then 1-2-3-4-5-6-7-8-9 and 10.

Wow Starry, a number line. 

But Starry, we can also draw the number line like this.

We draw the stretch horizontal line with arrows on both sides.

We start from 0 and then write the number at equal distances like this.

0-1-2-3-4-5-6-7-8-9 and 10.

Starry, the number line can be useful to us in many ways.

Today I show you how to add using the number line.

Suppose we have to add 3 plus 1 look at the number line begin from 3, move 1 place to the right.

What number do we reach Starry?

Yes, the number 4. So 3 plus 1 equals 4.

Next we will add 2 plus 3.

Start from 2 move to 3 places to the right 1-2-3, we reach the number 5. So 2 plus 3 equals 5.

Wasn’t that easy Starry?

And now Starry, 3 plus 4.

We start from 3 and we move 4 places to the right 1-2-3-4, we reach the number 7. So 3 plus 4 equals 7.

Now Starry shall we do an activity together.

We have the first add the objects by counting them.

We have to the next add the same objects using the number line.

Let’s begin with butterflies.

1-2-3-4-5 butterflies plus 1-2 butterflies.

5 plus 2 that is 1-2-3-4-5-6-7 butterflies. So 5 plus 2 is 7.

Now on the number line 5 plus 2. We start at 5, we move 2 places to the right 1-2.

We reach the number 7. So 5 plus 2 equals 7.

Next we have bows Starry. We have 1-2-3-4 bows plus 1-2-3-4 bows.

4 plus 4 that 1-2-3-4-5-6-7-8 bows. 4 plus 4 equals 8.

On the number line 4 plus 4.

We start at 4 and move 4 places to the right 1-2-3-4 we reach the number 8.

So 4 plus 4 equals 8.

Let us count now the leaves Starry?

1-2-3 leaves plus 1-2-3-4-5 leaves.

3 plus 5 leaves that is 1-2-3-4-5-6-7-8 leaves. 3 plus 5 equals 8.

Now the number line 3 plus 5, start from 3 move 5 places to the right 1-2-3-4-5, we reach the number 8.

So 3 plus 5 equals 8.

What do we have here some flowers Starry!1-2-3-4 flowers plus 1-2-3-4-5 flowers.

4 plus 5 flowers is 1-2-3-4-5-6-7-8-9 flowers. 4 plus 5 equals 9.

Let us now add on the number line. Start at 4 move five places to the right.

1-2-3-4-5 we reach the number 9. 4 plus 5 equals 9.

Finally stars 1-2-3-4-5-6 stars plus 1-2 stars, 6 plus 2 equals 1-2-3-4-5-6-7-8 stars.6 plus 2 equals 8.

Now on the number line, 6 plus 2 start at 6 move 2 places to the right 1-2 we reach the number 8.

So 6 plus 2 equals 8.

Excellent, you have now learnt to add on the number line.

So Starry, remember the number line is very useful to us, it helps us with addition

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