NCERT solutions for Math - Magic [English] Class 4 chapter 12 - How Heavy? How Light? [Latest edition]

Father gave them some idea of the weight of each thing.

Find out the total weight they had loaded on the cart.

Which things should be removed so that the weight of the load is not more than 700 kg?

Now, you also make your own balance. Write down how you made it. Also draw a picture of your balance in the box below.

Mannu and Jaiju put a pencil and geometry box in the two pans of the balance. Which pan will go down? Why? Draw a picture to show it.

Make pairs of different things and use the balance to decide which is heavier. First guess which thing will take the pan down and then check with your balance.

Make groups of three things. For example - eraser, ball and paper. Use the balance to arrange them in order of weight-the lightest, the one with in-between weight, the heaviest.

Complete the table with at least five examples.

Can you find your own weight using this balance?

Get a new cake of soap. The packet will have the weight written on it. You can use this soap to make your own different weights.
The soap weighs grams(g).

Take a small plastic packet.

Put it in one pan of the balance. Put the soap in the other pan. Slowly add sand to the packet till the pans are balanced.

Close the packet with a rubber band or string. Now stick a strip of paper and write ‘ g’ on it.

If you put the soap and the weight you just made together in a pan, how many grams will both these weigh?

Use your weights to weigh different things and write in your notebook.

Which pan of the balance will go down? Show by drawing an arrow.

Is the weight on any of the pans equal to 1 kilogram? Mark it.

 How many grams are there in 1 kg?

Name 5 things that we usually buy -

Which is heavier? One kilogram cotton or one kilogram iron?

Guess and write the weight of each thing he bought - in g or kg.

Ritu is weighing her toys. She wants to know if her tractor is heavier than her car. How would you help her to find out quickly?

Guess which is the heaviest-a real car, a bus or a tractor?

Which is the heaviest thing you have seen?

Now imagine what happened next and complete the story. Discuss with your friends how Vaidika’s daughter found the weight of the elephant.

Anamika wants to weigh this chair using the weighing machine. Can you suggest a way for doing this?

Now you show how Abdu will use these stone pieces to weigh —

4 kg of firewood -

Now you show how Abdu will use these stone pieces to weigh —

3 kg of firewood.

Now you show how Abdu will use these stone pieces to weigh —

Have you ever been to a post office?

What different things do people go there for?

How much does a postcard cost?

How much does an inland letter cost?

How much will you have to pay for stamps on a letter weighing 50 grams?

Akash wants to send a parcel of the Math Magic textbook to his friend Rani in Chennai. The book weighs 200 g. See the chart to find the cost of posting the book.

Read the weight shown in the picture. Find out the cost of sending a parcel of that weight.

Parcel weight = ______

Cost of stamps =  ______

Rahul needs stamps of Rupees 25 for his parcel. He went to the post office. Only stamps of Rs 1, Rs 2, Rs 5 and Rs 10 were there at that time. Using those stamps in how many different ways can he make Rs 25? 

Can you show five different ways? What is the heaviest parcel he can send using stamps of Rs 25?

A frog was struggling to escape from the mouth of a crow. How can I escape? The frog thought. Suddenly a trick came to his mind. He asked the crow-Are you good at arithmetic? If yes, then I will ask you a problem.

Your weight is 650 g and I am only 145 g. How much do we weigh together? The crow was good at mathematics, so he happily opened his beak to answer.

What happened after that? So what was the answer the crow wanted to give?

The chart shows the height and weight of children between 6 and 10 years old.

Now, you also fill the table by finding out the age, height and weight of any five friends. 

All oranges have equal weight. The two papayas have the same weight. The weights in the first and second balances are equal.

How many oranges balance the weight in the third?

There are 3 marbles of the same size but one marble is slightly heavier or lighter than the other two. Can you find which is that marble and if it is heavier or lighter? You can use a balance only two times.