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CBSE Class 4 · Science

How Things Work

Official NCERT chapter from Our Wondrous World (book code deev1). ExamMaster notes are original teaching at CBSE Class 4 depth.

This lesson follows the official chapter “How Things Work” in Our Wondrous World. The words below are ExamMaster’s teaching, not a paste from the book. Use the NCERT chapter for the classroom sequence; use these notes to hold the idea without copying exercises or figures.

  • CBSE Class 4
  • Easy level
  • 8 concepts

1A thing works because a cause makes a change

A switch, a push, or wetness is a cause. A lamp lighting or paper tearing is a change. Work means you can name both.

A brand name is not a cause.

Figure. A thing works because a cause makes a change you can name. Here a centred push is the cause and a long, steady spin is the change.

How it works

  1. Name the causePush, wet, flip.
  2. Name the changeMoves, soaks, lights.
  3. If you cannot name both, you have not explained the workLook again.

2Paper in this unit is a material with a making-story later

Paper is a material you can test now: tears, soaks, bends. How it was made waits for the next chapter.

Do not skip the test to tell a factory tale.

Figure. In this chapter paper is a material you test. How paper is made is a later chapter — do not mix the two jobs.

How it works

  1. Hold the paperThe material.
  2. Run one testTear, soak, or bend.
  3. Leave making-steps for laterShape, press, dry.

3Name the change before the gadget

“The paper got wet” is a change. “The brand of dropper” is a gadget-word. Change first.

A gadget without a named change is a toy mention.

Figure. Name what changed first — it stayed upright — then name the gadget. The science is the change, not the toy's name.

How it works

  1. See what is different afterThe change.
  2. Then name what you usedThe object.
  3. Keep that orderChange, then gadget.

4A path or a push has to be complete

A push that does not reach the toy does not move it. A water path that leaks before the cloth does not soak that cloth.

Incomplete path, no honest change.

Figure. A path has to be complete. A paper boat with dry walls keeps water out and floats. A hole is a broken path: water enters and the boat sinks.

How it works

  1. Trace the pathFrom cause to object.
  2. Ask if it arrivesComplete?
  3. If it breaks, name the breakDo not claim the change.

5A property you can test: bends, soaks, tears

Bend, soak, tear are tests on this paper or cloth. Run one at a time.

A story about a factory is not a property-test.

Figure. A property is a test you can run on the same sheet: it bends, it soaks, it tears. Write what you did, not what you hoped.

How it works

  1. Pick one property-wordBends, soaks, or tears.
  2. Run itFold, drip, or pull.
  3. Record pass or failThat is the property.

6The material is not the object

Paper is a material. A paper boat is an object. “Bring the paper” when you mean the boat mixes the words.

Same split as last year’s things-chapter, now on working.

Figure. The material is not the object. Paper is the stuff; a boat, a bag and a page are objects made from it.

How it works

  1. Point to the sheetMaterial.
  2. Point to the boatObject.
  3. Say both if you need bothBoat of paper.

7One classroom case

One sheet you tore, or one toy you pushed, is enough. You do not need every gadget in a shop.

A case with cause and change beats a list of brands.

Figure. One classroom case: two equal cards. A hole at the centre spins steadily. A hole off-centre wobbles and stops. Same card, different cause.

How it works

  1. Pick one thingThis paper, this toy.
  2. Name cause and changeThe work.
  3. StopNo shop tour.

8A miss: naming the brand as the science

A brand tells who sold it. It does not name cause or change. “It works because it is Brand X” is a miss.

Peel the brand; keep the test.

Figure. A miss: naming the brand as the science. Brand X is a label. Dry, wide walls are why the boat floats.

How it works

  1. Hear a brandA shop word.
  2. Ask cause and changeThe science.
  3. If only the brand remains, call the missNo work explained.
A thing works when you can name
  1. A cause and a change
  2. Only the brand
  3. Only the shop

Cause makes a change.

Notes

  • Mapped to the official NCERT chapter “How Things Work”. Original teaching only — no textbook sentences.
  • Science here is Physics, Chemistry and Biology ideas at this class, never a language or social-science chapter.

Recap

Hold these pegs from the official chapter “How Things Work”. The wording is ExamMaster’s teaching, not a textbook recap.

A thing works because a cause makes a change
A switch, a push, or wetness is a cause. A lamp lighting or paper tearing is a change. Work means you can name both.
Paper in this unit is a material with a making-story later
Paper is a material you can test now: tears, soaks, bends.
Name the change before the gadget
“The paper got wet” is a change. “The brand of dropper” is a gadget-word. Change first.
A path or a push has to be complete
A push that does not reach the toy does not move it.
A property you can test: bends, soaks, tears
Bend, soak, tear are tests on this paper or cloth.
The material is not the object
Paper is a material. A paper boat is an object. “Bring the paper” when you mean the boat mixes the words.

Practise How Things Work

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  • A 4-question practice set that ends the chapter
  • 1 quick check with worked explanations
  • Timed mocks scored with the real marking scheme
  • Readiness tracked per topic, kept on your device
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