Light Things Float Notes & Questions | Class 1 Physics | Drishti OS

Light Things Float

NCERT anchor: NCERT Looking Around Class 1 — Theme: Water Around Us (why light objects float)

What you'll learn

Light things like a dry leaf, a feather, or a paper boat usually float.
Air trapped inside an object (like a balloon or a ball) helps it float.
Floating things are useful — boats carry people across water.

Key concepts

1. Light objects on water

Level 1 (Verbal): A dry leaf is light, so it floats on a puddle.

Level 2 (Symbolic): Light + not soaked with water = usually floats.

Visual: A rubber ball bobbing on top of water.

2. Air helps floating

Verbal: A balloon filled with air floats on water because of the air inside it.

Symbolic: Air inside an object can help it stay up.

Visual: An inflated ball floating in a swimming pool.

3. Floating is useful

Verbal: Boats and ships are built so they float and can carry people and goods.

Worked example

A paper boat race

Step 1 — Fold a paper boat — it is light.
Step 2 — Place it gently on a puddle of water.
Step 3 — The paper boat stays on top and floats.
Step 4 — A friend's boat, once soaked with too much water, gets heavy and sinks.
Answer: light, dry things float; once soaked and heavy, they can sink.

Common mistakes

Mistake	Why	Fix
Thinking only tiny things float	Big light things like empty bottles also float	Check if it is light for its size, not just small
Believing floating things can never sink	A floating object can sink if it fills with water	A paper boat sinks once it gets too wet
Ignoring the role of air	Air trapped inside helps objects float	Remember: air inside helps things stay up

Quick check

Name two light things that float on water.
Why does an inflated balloon float?
What can happen to a paper boat if it stays in water too long?
Stretch: Why do empty plastic bottles float even though they are made of hard plastic?

Revision tip: Say aloud: 'Light and dry usually means it floats.'

Open the Practice tab for graded questions on Light Things Float.

Light Things Float