NCERT Solutions for Class 4th The World Around Us Chapter 7 Let us create some boats — Activity 5
Book page 113–114 Updated on2026-09-19
Q1.
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.
Answer
What to do, step by step
Sit in a group of three or four. Put all your material on one desk.
Talk about what your boat will look like. Decide its shape and its size.
Draw a picture of your boat in your notebook first, and mark which material goes where.
Build the boat. Make the bottom wide and flat so it does not tip over.
Seal the joints well with tape or clay so water cannot get in.
Test it in a tub of water. Fix anything that leaks or tips.
Put all the boats on one table with name cards, and invite the other classes to see them.
Three kinds of boats shown in the book that a group can make.
Sample answer: Our group made a raft from twelve ice-cream sticks. We laid the sticks side by side and joined them with two sticks across the back and adhesive tape. We pressed a small lump of clay in the middle to hold a paper flag. The raft floated flat on the water and did not tip even when we put two erasers on it.
Why it happens: A boat floats because it is hollow or flat and wide, so it spreads its weight over a lot of water — exactly like the foil cup in Activity 4.
Tip: Coconut shells, walnut shells and a big leaf all make good boats. They are hollow and light.
Q2.
Compare your boat with others’ boats.
Answer
Fill in the table after looking at your boat and at two or three other groups’ boats.
A completed sample table
Strengths of your boat
Challenges of your boat
Its bottom is wide and flat, so it does not tip over
Water slowly comes in between the sticks
Ice-cream sticks are strong, so the boat does not break
It is heavy, so it sits low in the water
It can carry two erasers without sinking
The tape comes off after it is wet for a long time
What we noticed when we compared:
The paper boat was the lightest but it became soft and sank first.
The coconut-shell boat floated best because it is hollow.
The clay boat sank when it was rolled into a lump, and floated when it was made like a bowl.
Why it happens: The book says it too — some boats are strong and hard to break, while others break easily; some tip over easily, while others keep better balance.
Q3.
Think about how you can improve your boat.
Answer
Here are changes that really make a boat better. Try one change at a time and test it.
Make the bottom wider and flatter. A wide bottom keeps the boat from tipping over.
Seal every joint. Cover the gaps with tape or a thin layer of clay so no water comes in.
Keep both sides the same. If one side is heavier, the boat leans and flips.
Use lighter material. Thermocol, cork and a coconut shell float much better than thick clay.
Raise the sides a little. Higher sides keep water and waves out.
Place the load in the middle. Weight kept in the centre keeps the boat level.
Two boats of the same size put into water, one with a narrow bottom and one with a wide, flat bottom.
Why it happens: Each of these changes works on the boat’s shape and balance — and shape is what decides whether a thing floats or sinks.
Check it yourself: Put one coin at a time in your boat. Count how many coins it can carry before it sinks. Then improve the boat and count again.