Chapter 7: How Things Work
Explore spinning, floating, and sinking through fun experiments!
Chapter Summary
This chapter explores how everyday things move, spin, float, or sink. Through simple and fun experiments, students observe toys and objects to discover how shape, weight, balance, and material affect movement. Activities include spinning tops, floating/sinking tests, and designing boats, encouraging critical thinking and hands-on learning.
Let Us Answer
Page 105: Objects That Spin
Objects that can spin:
Ans: Coin, Bangle, Spinner, Pencil (when balanced), Top
Observation Table Sample:
| Object | I Observe | I Wonder | I Think |
|---|---|---|---|
| Coin | Starts shaking as it slows | Why does it wobble? | It loses speed and balance |
| Bangle | Makes sound and slows quickly | Why is it louder than coin? | It’s hollow and wide |
| Pencil | Doesn’t spin well | Why doesn’t it rotate? | Uneven shape |
| Stone | Rolls but doesn’t spin | Why not spin? | Shape not round |
| Wooden spinner | Spins well and balances | Why is it stable? | Has balanced center and shape |
| Eraser | Doesn’t spin | Why not move? | Too soft, not round |
Page 106–108: Spinner Experiments
Spinner Designs:
| Spinner Type | Spins? | Observation |
|---|---|---|
| Toothpick at centre | Yes | Balanced, spun well |
| Toothpick off-centre | No | Wobbled, fell quickly |
| Square spinner | Yes | Appears circular while spinning |
| Circular spinner with markings | Yes | Colours mix visually when spinning |
Spinner that didn’t spin properly?
Ans: The one with the off-centre hole—unbalanced.
Does shape affect spinning?
Ans: Yes, symmetrical shapes spin better.
Page 109–112: Floating and Sinking
Common Objects and Predictions:
| Item | Guess | Observation | Reason |
|---|---|---|---|
| Leaf | Float | Float | Very light |
| Iron nail | Sink | Sink | Heavy, dense metal |
| Empty steel bowl | Sink | Float | Shape helps displace water |
| Stone | Sink | Sink | Heavy, dense, no air trapped |
| Empty bottle with lid | Float | Float | Air trapped inside |
| Full water bottle (closed) | Sink | Sink | Heavy, displaces less water |
Page 112: Aluminium Foil Shape Test
Foil Shape Test:
| Foil Shape | Guess | Observation | Reason |
|---|---|---|---|
| Spread out | Float | Float | Large surface, spreads weight |
| Pressed ball | Sink | Sink | Compact, small area, less displacement |
| Cup shape | Float | Float | Traps air, acts like a boat |
Page 113–114: Make a Boat Activity
Boat Materials:
Ans: Paper, cardboard, coconut shell, walnut shell, clay, sticks, foil, tape
Compare Boats:
| Strengths | Challenges |
|---|---|
| Stays balanced, doesn’t tip easily | Weak material, soaked quickly |
| Strong design | Needed more tape to seal |
| Used waste items | Needed adjustments for floating |
Page 115: Reflective Questions
Ravi’s questions about spinning:
Ans:
- Why does the spinner stop?
- What helps it stay balanced?
To balance figure A:
Ans: Add weight on side B to balance both sides.
Make sinking object float:
Ans: Change shape to increase surface area or trap air (e.g., foil cup).
Page 116: Float vs Sink Classification
Float vs Sink:
| Float (F) | Sink (S) |
|---|---|
| Thermocol | Marble |
| Wax | Coin |
| Cork | Eraser |
| Leaf | Spoon |
| Ice cube | Potato |
| Lemon | Tomato (may float or sink depending on size) |
| Pumpkin | Usually floats |
Activities
Page 106–108: Spinner Experiments
Activity: Create and test different spinner designs (e.g., toothpick at centre, off-centre, square, circular with markings).
Instructions: Use cardboard, toothpicks, and markers to make spinners. Spin them, observe balance and colour blending, and record findings in a table.
Tip: Colour different spinners and observe how colours blend visually when spinning.
Page 109–112: Floating and Sinking
Activity: Test objects (e.g., leaf, iron nail, empty bottle) to see if they float or sink in water.
Instructions: Fill a tub with water, predict if objects will float or sink, test them, and record observations and reasons in a table.
Page 112: Aluminium Foil Shape Test
Activity: Shape aluminium foil into spread-out, pressed ball, and cup forms, then test if they float or sink.
Instructions: Use small pieces of foil, shape them as described, place in water, and note why each shape behaves differently.
Page 113–114: Make a Boat Activity
Activity: Design and test boats using materials like paper, cardboard, coconut shell, or foil.
Instructions: Build boats, decorate them, and test in a water tub or bucket. Compare strengths and challenges, and hold a boat exhibition. Use tape to seal if needed.
Tip: Decorate boats with colours and patterns for the exhibition.
Let Us Reflect
Students can reflect on the chapter by discussing how shape, weight, and balance affect spinning and floating, and how experimenting helps understand everyday objects.
Concepts Covered
- Spinning objects and balance
- Design and function of toys (like spinners/tops)
- Floating and sinking: material, shape, weight
- Hands-on exploration with boats and household items
- Creative design and comparison of results
- Hands-on activities: Spinner experiments, floating/sinking tests, boat design
