Class 4 EVS Chapter 7 Solutions: How Things Work (Stepwise Answers & PDF)

Activity 1 (Page 105)

Question 1. Do you think all objects can spin? Make a list of a few objects that can spin.

Answer: No, all objects cannot spin. Some objects can spin easily, while others do not spin at all.
Few objects that can spin:

• Coin

• Bottle cap

• Lattu

• Football

• Ceiling fan

Question 2. Collect the objects mentioned in the table given below. Spin and observe them. Then, complete the table.

Answer:

Activity 2 (Pages 106 – 107)

Collect things, such as pieces of cardboard, toothpicks, an empty tube of a ballpoint pen, and other small objects. Make the following spinners. Spin them and record your observations.

Answer:

Discuss (Page 10.8)

Question 1. Which of the spinners did not spin properly? Discuss the possible reasons.

Answer: The spinner did not spin well when the toothpick was placed away from the centre because it was unbalanced. When the hole is not in the middle, the spinner wobbles and falls over quickly.

Question 2. Have you noticed the position of the hole in the first two spinners? Did this difference in the position of the hole make a difference in the spinning of these spinners?

Answer: Yes, I observed the difference in the position of the hole in the first two spinners. The first spinner had the hole at the centre, which kept it balanced and allowed it to spin for a longer time. However, the second spinner had the hole away from the centre, so it was unbalanced and did not spin properly. This shows that the position of the hole makes a big difference.

Activity 3 (Pages 110-111)

Collect objects, such as a leaf, an iron nail, an empty bowl (katori), a plastic bottle with a lid, pieces of stone, aluminium foil and other things of your choice. Fill a bucket with water. Before dropping the things listed in the table, guess whether things will float or sink. You may try other things too. Then, observe what happens when it is actually dropped in water. You can write ‘F’ for objects that float and ‘S’ for objects that sink.

Answer:

Discuss (page III)

Did all the light objects float and all the heavy objects sink? Name the heavy objects that floated and lighter objects that sank.

Answer: No, all the light objects did not float and all the heavy objects did not sank.

• An empty steel bowl was heavy but it floated.

• An iron nail or pin was light but it sank.

Activity 5 (Pages 113 -114)

Question 1. Let us create some boats:

• Collect some paper, cardboard boxes, ice-cream sticks, clay, adhesive tape, etc.

• Create groups of three to four students.

• Think of how you can make a boat using some of the materials that you have.

• Draw a picture.

• Prepare a boat. Try to ensure that your boat is different from boats made by other groups.

• Organise an exhibition of boats in the class.

Following are some different types of boats which can be made.

Answer: Students should do it by themselves.

Question 2. Compare your boat with others boats.

Answer: Students should do it by themselves.

Let Us Reflect (Pages 115-116)

1. Enquire about something

When Ravi spins a spinner, he notices that it slows down and eventually stops. He is curious about this and asks his teacher some questions. List at least two questions that he could ask.

Question 1. Why does the spinner slows down after sometime?

Question 2. What makes the spinner stop spinning?

2. Figure It out
(a) The following figure is bending towards the side ‘A’. What should be done to balance it?

(b) How would you make a floating object sink and a sinking object float?

Answer:

(a) To bring the balance into equilibrium, we can place an extra load on side B, take away the object from side A, or shift the weight closer to the centre point of the balance.

(b)  If we want an object that floats to sink, we can increase its mass by adding weight or alter its shape so it displaces less water.

To help a sinking object float, we can attach a lightweight material such as a sponge or modify its shape so it can stay on the surface.

Do an activity

Classify the objects below based on whether they float or sink in water.

Answer:

Understanding How Things Work: A Student-Friendly Guide

Chapter 7 of Class 4 EVS explores how different things work in our daily lives. With fun experiments on spinning, floating, and sinking, students develop a curiosity for science while easily understanding real-world concepts.

Practicing these activities makes learning about spinners, boats, and floating objects both engaging and valuable. By doing hands-on tasks, children grasp the reasons behind everyday phenomena—making their NCERT EVS preparation even stronger.

Revise all key questions and try the suggested activities for the best exam results. Understanding how things work not only boosts your exam confidence but also helps you observe and question the world around you.