10. Tenths and Hundredths

What was the length of the smallest pencil you have used?

How long is this pencil ? Guess _____ cm

Measure it using a scale. How good is your guess?

We can see that Anju used a lens to make it look bigger.

It is more than 3 centimetres.

Here one centimetre has 10 equal parts. So each part is one-tenth of a centimetre.

One-tenth of a centimetre is called one millimetre (mm).

Oh, so this pencil is 3 centimetres and 6 millimetres long.

See I am 3 mm long!

But I am longer! Seven-tenth of a centimetre or _____ millimetres

We also call one-tenth of a centimetre as 0.1 centimetre. We read it as ‘zero point one centimetre’.

So one millimetre is the same as 0.1 cm.

1. What is the length of this pencil? _____ mm.

What is its length in centimetres?

What does 0.9 cm mean? It is the same as _____ millimetres. We can also say this is nine-tenths of a cm. Right?

So 30.5 cm is the same as _____ cm and _____ millimetre.

About how many of the big frogs will fit on the 1m scale? _____

If they sit in a straight line about how many of the small frogs will cover 1m? _____

Practice time

1) Length of the - nail cm and _____ mm or 2. _____ m.

2)

The length of this lady's finger (bhindi) is _____ cm and _____ mm. We can also write it as _____ cm.

3) Using the scale on this page find the difference in length between candle 1 and candle 3.

Guess and Colour

First colour the rods as shown, without measuring! Then check.

Rods of length less than 1 cm Red

Rods of length between1 cm and 2 cm Blue

Rods of length between 2 cm and 3 cm Green

Rods of length between 3 cm and 4 cm Orange

Guess, Draw and Measure

Guess the lengths to draw these things. Ask your friend to draw the same. After you make the drawing use a scale to measure the length. Whose drawing showed a better guess?

Whose Tail is the Longest?

Guess whose tail is the longest. Now measure the tails. How good is your guess?

The Longest Rupee Notes?

What is the length of a 100 rupee note? Guess.

Now measure it using a scale.

Now guess the length and width of many other things. Measure and find the difference between your measure and your guess.

At the market

Look at this funny price! 32 rupees and 99 paise! But if we give 33 rupees they don’t give us back one paisa!

What part of a rupee is 1 paisa?

This is only to fool us by showing 1 paisa less!

One paisa is one hundredth of a rupee, isn’t it?

It is written as Rupee 0.01. So that is why we write 99 paise as Rupee 0.99

1) How many paise does a matchbox cost? _____

2) How many matchboxes can be got for Rs 2.50? _____

3) How many rupees does the soap cost? _____

4) Arun wanted to buy a soap. He has a five-rupee coin, 2 one-rupee coins and 4 half-rupee coins. Write in rupees what money he will get back.

5a) An egg costs two and a half rupees. How much will one and a half dozen cost?

b) How many pens can Kannan buy? How much money is left?

Kannan, take rupees 60 and buy one and half dozen eggs. You can buy pens with the money left.

S

Can I buy two pens with rupees 13?

6) The price of two pens is Rs _____ Can she buy two pens?

Practice time — Match these

Match each yellow box with one green and one pink box

Colourful Design

What part of this sheet is coloured blue? _____ /10

What part of the sheet is green? _____

Which colour covers 0.2 of the sheet?

Oh, the blue strip is 0.1 of the sheet.

Now look at the second sheet. Each strip is divided into 10 equal boxes. How many boxes are there in all?

Is each box 1/100 part of the sheet?

How many blue boxes are there? _____

Is blue equal to 10/100 of the sheet? We saw that blue is also equal to 1/10 of the sheet. We wrote it as 0.1 of the sheet.

Can we say 10/100 = 1/10 = 0.10 = 0.1?

Think: Can we write ten paise as 0.1 of a rupee?

How many boxes are red? What part of the sheet is this? 15/____

Can we also write it as 0.15 of the sheet?

(Hint: remember we wrote 99 paise as 0.99 rupee!)

Now 3/100 of the sheet is black. We can say 0. _____ sheet is black.

How many white boxes are there in the sheet?

What part of the second sheet is white? _____

* Make your designs.

Make a nice design by colouring 0.45 part of this square red.

Use four colours. Each colour should cover 0.05 of this square.

Sports Day

The school at Malappuram has its sports day.

The first five children in the Long Jump are:

Teena jumped 3.50m which is 3 m and 50 cm.

But how did Anu jump? _____ m and _____ cm

Who is the winner in the long jump? _____

Write the names of the I, II and III winners on this stand.

Write in Metres

3 metre 45 centimetre _____ metres

99 centimetre _____ metres

1 metre and 5 centimetre _____ metres

How Big Can You Get

A)

After breathing out 1.52 m

On taking a deep breath 1.82 m

Difference in size _____

Do this for yourself and find the difference.

B) You have to grow 45 cm more to reach 2 m height

Practice time

1) Money from different countries

Have you seen any notes or coins used in any other country?

Shivam Bank has a chart to show us how many Indian rupees we can get when we change the money of different countries.

(This is the rate on 15-2-2008)

A) The money of which country will cost the most in Indian Rupees?

B) Mithun’s uncle in America had sent him 10 USA dollars as a gift.

Mithun used 350 rupees for a school trip. How much money was left with him?

Children are not expected to carry out long multiplication involving decimals. Instead, encourage them to think in terms of currency. For example, 75 paise × 2 can be thought of as two 50 paisa coins and two 25 paisa coins.

C) Majeed’s father is working in U.A.E. He gets 1000 Dirham as salary. Arun’s father who is working in Sri Lanka gets 2000 Sri Lankan Rupees. Who gets more Indian rupees as salary?

D) Leena’s aunty brought a present for her from China.

It cost 30 Yuan. Find what it costs in Indian rupees.

E) Astha wants some Hong Kong Dollars and Won.

1) How many Won can she change for Rs 4 For Rs 400?

2) How many Hong Kong Dollars can she change for Rs 508?

2) Kiran went shopping with Rs 200. Look at the bill. The shopkeeper forgot to put the point correctly in the prices. Put the point in the correct place and find out the total amount of the bill.

3) Which city is cool?

Children can be encouraged to look at temperatures (in degree Celsius or °C) of different cities in the news paper and on TV. Without using the terms' maximum' and 'minimum' this exercise will give them an idea that temperatures can be measured at two different times of the day. Only simple subtractions using decimals have been used here. They will also get familiar with the names of different capital cities and can do similar exercises for the capital cities of other countries.

The temperature in each city was noted at 3 pm on 16 January 2008.

1) Which place had the highest temperature at 3 pm? Which place is the coolest at that time?

3) How many degrees will the temperature need to rise for it to reach 40ºC in Thiruvananthapuram?

4) How much lower is the temperature of Kolkata from that in Chennai?

5) The temperature in these cities was also noted at 3 am on the same day.

Look at the table and answer the questions.

a) Which place had the lowest temperature at 3 am? Imagine yourself to be there and describe how it would feel.

b) What is the difference between the temperatures at 3pm and 3am in Chennai? In Bhopal?