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Light is one of the friendliest chapters in Class 7 science because you can test almost everything with a torch and a mirror. It is also a chapter where students lose marks on words: luminous versus non-luminous, translucent versus transparent, inverted versus laterally inverted. This guide explains what the chapter covers, works through examples you can check at home, and lists the mix-ups to avoid.
What does Chapter 11 of Class 7 Curiosity cover?
Light: Shadows and Reflections is Chapter 11 of NCERT's *Curiosity* for Grade 7 (first edition April 2025, reprint 2026-27). It covers:
Luminous and non-luminous objects. The Sun, stars and fireflies give out their own light. The Moon does not; it reflects sunlight.
Light travels in a straight line, shown with three matchboxes with holes and a bent pipe.
Transparent, translucent and opaque materials.
Shadows, and what changes their size and shape.
Reflection by a plane mirror, and the properties of the image.
The pinhole camera, the periscope and the kaleidoscope.
The laws of reflection, with angles of incidence and reflection, are not in this chapter. They come next year, in Chapter 10 of the Class 8 book, "Light: Mirrors and Lenses".
How does a shadow form?
You need three things: a source of light, an opaque object and a screen (a wall or the ground will do). Because light travels in straight lines, it cannot bend round the object, so the region behind it gets no light. That dark patch is the shadow.
The chapter's activities show that:
Opaque objects make dark shadows; translucent objects make lighter ones; even some transparent objects make faint shadows.
Moving the object closer to the torch makes the shadow bigger. Moving it closer to the screen makes it smaller and sharper.
Changing the colour of an opaque object does not change the colour of its shadow.
What does a plane mirror do to an image?
The chapter lists four properties of the image in a plane mirror. It is the same size as the object, it is erect (upright), it cannot be obtained on a screen, and it is laterally inverted: your left hand appears as the image's right.
One more property, which the Class 10 book states directly, is that the image is as far behind the mirror as the object is in front of it. The Class 7 activity shows the same thing without numbers: stand closer and your image comes closer.
Worked examples
Example 1: distance in a mirror. You stand 1.5 m in front of a mirror. Your image is 1.5 m behind it, so you and your image are 1.5 + 1.5 = 3 m apart. You step 0.5 m closer. Now you are 1 m from the mirror, the image is 1 m behind it, and the gap is 2 m. You moved 0.5 m, but the gap shrank by 1 m.
Example 2: letters in a mirror. Write capital letters on a card and hold it facing a mirror. Which look the same in the mirror? Letters with a vertical line of symmetry: A, H, I, M, O, T, U, V, W, X and Y. Letters like B, C, D, E and K look reversed. This is why the chapter's question about T and O has the answer it has, and why "AMBULANCE" is painted reversed on the front of an ambulance: the driver ahead sees it the right way round in a rear-view mirror.
Example 3: the pinhole camera. Light from the top of a candle flame travels in a straight line through the pinhole and lands at the bottom of the screen. Light from the bottom lands at the top. So the image is upside down. If you can draw those two straight lines, you can explain any pinhole camera question.
Example 4: the bird's shadow. The chapter asks why you do not see the shadow of a bird flying high, but you do when it swoops low. When the bird is high, it is small compared with how far it is from the ground, and its shadow is faint and blurred into the surrounding light. Close to the ground, its shadow is sharp and dark. This is the same rule as the torch activity: an object near the screen makes a sharper shadow.
What mistakes do students make about light?
Students arrive with their own ideas about light and seeing, and teaching does not always change them. Galili and Hazan (2000) studied high school and teacher-training students' knowledge of light and vision before and after the usual instruction, and suggested teaching that challenges the underlying patterns of thinking rather than one misconception at a time. In practice, that means making a prediction, testing it with a torch, and explaining the result.
The common slips in this chapter:
"The Moon is luminous." It shines only by reflecting sunlight.
"A red ball makes a red shadow." Shadows do not take the object's colour.
"The image is on the surface of the mirror." It appears behind the mirror, as far behind as you are in front.
"A plane mirror makes things upside down." It does not; a pinhole camera does.
"Translucent and transparent mean the same." Transparent lets light through almost completely; translucent lets some through.
A one-week practice plan
Day 1: In a dark room, make shadows with a torch. Move the object nearer the torch, then nearer the wall, and write what happens.
Day 2: Do Example 2 with your own name. Which letters stayed the same?
Day 3: Make a pinhole camera from two boxes, as the chapter describes, and look at a tree in sunlight.
Day 4: Answer the chapter questions from memory and check.
Day 5: Explain to a parent why a periscope needs two mirrors.
For the next step, read our Class 8 light guide. If light paths are hard to imagine, the Fermi Simulation Lab has interactive simulations for ideas that are easier to see than read.
Tonight, write your name on a card, hold it up to a mirror, and predict which letters will look the same before you look.
