ML Math Lab — Magic Door
Precision vs Recall as a beautiful, easy-to-understand security gate game (English explanations locked)
Mode: Explore
Goal: balance Precision & Recall
Score: 0
Section 1 — What you will learn
By the end you will understand
  • Precision: out of all “YES”, how many were truly correct?
  • Recall: out of all real “YES”, how many did we catch?
  • False Positive: door said YES to a bad item (oops).
  • False Negative: door said NO to a good item (missed).
  • Trade-off: stricter door ↑Precision but ↓Recall (often).
Section 2 — Controls
Same concept, Challenge adds scoring + “Win” fireworks.
Lower threshold → catch more good (higher Recall) but also catch more bad (lower Precision).
When positives are rare, false positives can hurt Precision a lot.
Low skill = scores overlap → trade-off becomes painful.
Slow it down if you want to read every decision.
How to play: Start the stream, then move the Threshold slider. Watch which box (TP/FP/FN/TN) lights up after each item.
The big strip above the arena tells you the meaning of each decision.

Section 3 — Live stats
Precision
Recall
TP / FP
FN / TN
F1 Score
Total Passed

Section 4 — Math (simple)
What the gate is calculating Live formulas
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🧠 Kid Coach
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Tip: Watch the big decision strip above the arena.
Section 5 — The Playground
Hover controls • Click inside arena to interact
Live explanation
Do an action → I’ll explain what changed and why.