Everyday Science Quiz

About Everyday Science Quiz

Give your memory a workout with Everyday Science Quiz: 15 multiple-choice questions with a mix of 7 easy, 6 medium, 2 hard questions, free to play right in your browser. Why does bread rise, why is the sky blue, and what makes ice float? Test the science behind daily life. Expect to spend about 7 minutes; every question comes with an explanation, so you learn something even when you miss.

A few sample questions

1. 1. Why does bread rise when you bake it?

   Answer: Yeast produces carbon dioxide gas bubbles that get trapped in the dough

   Yeast is a tiny living organism that eats sugars in the dough and releases carbon dioxide gas as a byproduct. Those gas bubbles get trapped in the stretchy gluten network, making the dough puff up beautifully.

2. 2. Why is the sky blue on a clear day?

   Answer: The atmosphere scatters blue light more than other colors of sunlight

   Sunlight contains all the colors of the rainbow, but blue light has a shorter wavelength that bounces off air molecules much more easily than other colors — a process called Rayleigh scattering. This scattered blue light reaches our eyes from every direction, making the whole sky look blue.

3. 3. Why does ice float on water instead of sinking?

   Answer: Frozen water expands and becomes less dense than liquid water

   When water freezes, its molecules arrange themselves into a crystal structure that takes up about 9% more space than liquid water. This makes ice less dense than liquid water, so it floats — a lucky quirk that keeps lakes from freezing solid and allows fish to survive winter.

4. 4. What makes a cut apple turn brown after you slice it?

   Answer: Enzymes in the apple react with oxygen in the air

   Apple cells contain an enzyme called polyphenol oxidase. When you cut the apple, you break open cells and the enzyme comes into contact with oxygen in the air, triggering a chemical reaction that produces brown-colored compounds. A squeeze of lemon juice slows the browning because the acid blocks the enzyme.

5. 5. Why does a woolen sweater make crackling sounds and sparks when you pull it off in the dark?

   Answer: Static electricity builds up as the sweater rubs against your hair and skin

   As the sweater slides over your hair and skin, electrons transfer from one surface to the other — this is called triboelectric charging. The built-up static electricity then discharges as small sparks and snapping sounds, especially noticeable in dry winter air.

Things you'll learn along the way

• ✓A flat mirror actually reflects you front-to-back — it swaps what is nearest the mirror with what is farthest. Because we imagine turning around to face ourselves (a left-right rotation), our brain interprets that front-back reversal as a left-right flip, even though the mirror itself treats all directions equally.
• ✓Friction is a force that resists sliding between two surfaces. When you rub your palms together, the energy of that motion is converted into heat — the same reason a match lights when struck, or why prehistoric people could start fires by rubbing sticks together.
• ✓That wonderful earthy rain smell is called petrichor. It comes mainly from geosmin, a compound produced by soil bacteria, which gets carried into the air when raindrops hit dry ground. A whiff of ozone from distant lightning also sometimes mixes in before a storm.