Entropy and the Direction of Change

Lab Brief #8

🎯 Your mission

Predict it first. Then prove yourself right (or wrong).

⚡ The twist

Nature loves to surprise the careful watcher.

What you'll learn

Energy spontaneously spreads out. The second law says total entropy — a measure of how dispersed energy is — never decreases in a closed system. That is why a hot drink cools to room temperature but a room-temperature drink never spontaneously heats up.

Key words

entropy
A measure of how spread out the energy in a system is.
second law of thermodynamics
Total entropy of a closed system never decreases.

Make a hypothesis first

Before you start: write down what you think will happen, and why.

Say your guess out loud — then find out if you were right.

Get ready

🧰 What you need

ink or food colouring
clear glass of still water
phone camera

Get ready

⚠️ Safety first

Food colouring stains — protect the work surface and clothing.

Step 1 of 4 · Read

Think about what you just learned: say what "entropy" and "second law of thermodynamics" mean in your own words before you start.

Step 2 of 4 · Do

Place a drop of ink in still water and photograph it every 30 s for ten minutes. Describe the sequence, then explain why the reverse film would look obviously wrong even though it breaks no conservation law.

Step 3 of 4 · Observe

Record what actually happened, including anything that did not match what you expected.

Step 4 of 4 · Record

Write a conclusion that answers the question this lesson opened with, and state your uncertainty.

Question 1 of 2

The second law of thermodynamics says entropy in a closed system:

How sure are you?😐 maybe

Question 2 of 2

A hot drink cools rather than heating because energy tends to:

How sure are you?😐 maybe

Mind = blown

🔬 The more you look, the more nature shows you.

Nice work!

You got 0 of 2 right.

All lessons

🎯

Next Smart Experiment

We'll pick an experiment that matches exactly how you're thinking right now.

✨ More to explore

🌍 Where you see this in real life: This shows up in your everyday life more than you'd think.

🏆 Stretch challenge (try it this week): Try one experiment in real life this week — even a tiny one.

👨‍👩‍👧 For the dinner table: “What's the most surprising thing you learned today?”

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