← Investigators TechnologyFrames and motion30 minutesStd 6–8

Stop-Motion Movie

✨ Twenty-four still photographs, played quickly, make a clay figure walk across the table on its own.

Two filmstrips of the same clay figure walking: the top strip has six frames with tiny position changes and looks smooth, the lower strip has three frames with big jumps and looks jerky, labelled twenty-four frames per second. — How it works

🧰 You need

an adult's phone camera
a small clay figure or toy
books to prop the phone steady
a plain sheet as a backdrop
tape to mark positions
a desk lamp or bright window

⚠️ Use an adult's phone with permission and keep the lamp cable out of the walkway.

👀 What you will see

Any accidental nudge of the phone shows up as a jump in the finished movie. Big steps between photos give jerky movement, while small steps look smooth. Steady light matters, because a change in brightness flickers on playback.

🧪 Do it

Prop the phone on books so it cannot move at all, and tape the backdrop in place.
Set your figure at the start and take one photo.
Move the figure a very small step and take another photo, without touching the phone.
Repeat until you have at least twenty-four photos of the same scene.
Swipe through the photos as fast as you can, or use a free stop-motion app to play them.
Shoot the same short scene again using twice as many photos and compare the two.

💡 Why it happens

Your eye and brain hold on to an image for a fraction of a second, so a fast sequence of stills blends into continuous motion. Each still picture in the sequence is called a frame, and cinema traditionally runs at 24 frames per second. The smaller the change between one frame and the next, the smoother the motion looks, which is why more frames per second of story means more work and a better result. Video files are simply long ordered lists of frames, compressed so that only the changing parts are stored.

🔁 Now try this

Film the same two-second action once with twelve frames and once with twenty-four, and judge which looks smoother.

🤔 Think about it

Why does a flipbook look jerky when you flick it slowly but smooth when you flick it fast?

🧘 Ask the Acharya

“Why does a flipbook look jerky when you flick it slowly but smooth when you flick it fast?” — ask him and he will explain it from your own chapters.

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