Bài 26: Measurement length (part 2)

Hey Stary! I want to buy a new table cloth, the old one has been torn a little.

But I’m not sure how big the table cloth should be?

Hey! I have an idea.

We shall fisrt measure the length of the table and then I can get the table cloth of that size.

Stary ! we shall measure the length of the table with a span.

A span is formed when the fingers are spead out.

The length of this table is 7 spans.

Hey ! we can also measure the length of the table using an arm-length.

An arm –length is also known as a cubit?

Let’s measure the length of the table.

The length of the table is 3 arm lengths , 3 cubits.

Chiều dài của bàn bằng chiều dài 3 cánh tay, 3 cubit.

Stary! Just like we use a span or an arm-length to measure the length.

we can also use the feet and pace for measuring the lengths.

Look at the picture shows here.

Ram is measing the length of his room using his foot.

the length of his room is 20 foot-lengths.

But stary! what if Ram had to measure the length of his garden.

Measuring the foot would take a long time.

So Ram measures the length of the garden with his pace.

It was 8 paces long.

Stary, can you think of any other ways in which we can measure the length ?

Yes, we can also measure the length using a pencil or a stick or a rod.

Stary! take a look at these 2 pictures.

In the 1st picture we see that the girl measured the length of the blackboard by using arm-lengths.

It lengths was 4 arm lengths.

In the 2nd pictures the teacher has measured the length of the same blackboard using her arm lengths.

Now the length of the blackboard is 3 arm lengths.

In the picture given here.

the length of the carpet was measured by the boy using his foot length.

The length was 12 foot lengths.

The same carpet was measured by the father using his foot length .

Now the length of the carpet was 9 foot lengths.

Can you tell Stary why is there a difference in the lengths of the same objects?

You are smart, Stary.

The number of arm-length or foot length counted by both the people in each people is not the same because the length of their arm or feet is not the same .

Hey Stary,See here are some chart papers.

let’s measure the length of this chart paper using a ruler.

The length of the chart paper is 2 ruler lengths.

What’s happen Stary ?

you have already measured of the length of the chart paper using the same scale.

What answer did you get ? 2 ruler lengths.

That’s great !

So it mean if we measure the length of the object with the same instrument then the measure remain the same no matter who measure it.

Stary ! Let’s now find the length of these rod.

The rods have been labeled A, B, C, D to identify them.

Let’s use the scale again.

The length of the rod A is 2 ruler length .

Now let measure the length of rod B.

The length of the rod B is 2 ruler lengths.

What is the measure of the 3rd rod, Stary?

It looks smallest. Hey ! Its length is only 1 ruler length.

Now, let’s measure the last rod.

The length is equal to the length of the rod B . that is 3 ruler lengths.

Stary ,our rod A and rod B which rod has less length.

Yes, the length of rod A is less than the length of rod B.

Our rod D & C whose length is more?

yes, the length of rod D is more than the length of rod C.

Stary, Here are the name of some articles,

you have to give the best possible method of measuring their lengths.

+ The first one is a book.

How we use measure in the length Stary?

yes, by using the span of your hand.

+ The height of cupboard is the best measure by an arm-length.

+ What about the length of the ground, Stary?

yes, we measure it by using the pace of the foot.

+ The last is the length of ribbon.

We can measure it using an arm-length.