🎒 What you need

about 20 stones and 20 leaves, mixed in a heap
a flat patch of ground or floor
a stick to draw a line

✋ Do this

Draw one long line in the dust with your stick. Left side, right side.
Mix your stones and leaves into one messy heap. Really mix them.
Now sort. Stones left, leaves right. Do it as fast as you can while someone counts.
Say the rule out loud: 'If it is hard, go left. If it is soft, go right.' That sentence is the whole thing.
Point at your two neat piles. That picture is what a machine makes inside itself, every single time.
Now try a mean trick: put in one dry, hard leaf. Which pile? Argue about it with someone.

💡 Why it works

A sorting machine has no eyes and no opinions. It has a rule, like 'hard goes left', and it follows that rule on every single thing you hand it. The dry hard leaf is the interesting part — real machines get confused by exactly that kind of in-between thing, and people who build them spend most of their time on those.

🔥 Challenge

Sort the same heap again but with a brand new rule — by size, or by colour. Can a friend guess your rule after watching you sort only five things?

📖 New words

sortto put things into groups that belong together

rulethe one sentence you follow every time, no exceptions

🥇

Pile Boss

Tap when you have finished this module.