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Science Mysteries

Pick a mystery. Have a guess before you peek — that guess is the whole point.

🌊

Density & Floating

Physics

Whether something floats depends on density — and you can come at that one idea from four different directions.

  1. 1

    Why does ice float?

    Tier 2 · water

  2. 2

    Why does a giant steel ship float when a tiny coin sinks?

    Tier 2 · water / forces / density

  3. 3

    Why does a huge, heavy hot-air balloon rise into the sky?

    Tier 2–3 · air / forces / density

  4. 4

    Why do you float more easily in the sea than in a swimming pool?

    Tier 2 · water / forces / density

🌈

Light & Colour

Physics

Light travels in straight lines until it meets something — then it scatters, bends or splits, and that is where colour comes from.

  1. 1

    Why is the sky blue?

    Tier 2 · light

  2. 2

    Why do sunsets turn red?

    Tier 2 · light

  3. 3

    Why does a straw look bent in a glass of water?

    Tier 1–2 · light

  4. 4

    How does a rainbow form?

    Tier 2–3 · light

💧

States of Matter

Chemistry

Matter moves between solid, liquid and gas as energy is added or taken away — and gases can even hide dissolved inside liquids.

  1. 1

    Why do puddles dry up, even on a cold day?

    Tier 2 · water / states

  2. 2

    Why can you see your breath on a cold day?

    Tier 2 · water / states

  3. 3

    Why does dry ice make fog?

    Tier 2–3 · states / gases

  4. 4

    Why does a fizzy drink go flat?

    Tier 2 · gases / states

🫀

How Your Body Works

The Human Body

Your body is constantly adjusting itself to stay balanced — and many of the odd things it does are automatic self-regulation you never decide to do.

  1. 1

    Why do you get goosebumps?

    Tier 2 · skin / body

  2. 2

    Why do you shiver when you are cold?

    Tier 2 · body / heat

  3. 3

    Why does your tummy rumble?

    Tier 2 · digestion / body

  4. 4

    Why do you yawn?

    Tier 2–3 · brain / body

🌍

Day, Night & Seasons

Earth & Space

Earth's spin and its tilt — not how close we are to the Sun — create day, night and the changing seasons.

  1. 1

    Why do we have day and night?

    Tier 1 · Earth / space

  2. 2

    Why is summer warmer than winter?

    Tier 2 · Earth / space

  3. 3

    Why don't we feel the Earth spinning?

    Tier 2–3 · Earth / motion

  4. 4

    Why are summer days longer than winter days?

    Tier 2 · Earth / space

🦠

Meet the Microbes

Microbiology

The world is full of invisible living things — most harmless or helpful, a few harmful — and understanding them keeps us healthy and even feeds us.

  1. 1

    Why does bread go mouldy?

    Tier 2 · microbes / fungi

  2. 2

    Why do we wash our hands with soap?

    Tier 1–2 · microbes / health

  3. 3

    Why don't antibiotics cure a cold?

    Tier 2–3 · microbes / medicine

  4. 4

    Why does milk turn into yoghurt?

    Tier 2 · microbes / food

More clusters are on the way — light & colour, states of matter, the human body, and beyond.