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A warm workshop with a little toy conveyor belt of wooden boxes moving between shelves, two teenagers timing the line and finding where it slows

🎓 Ages 15–18 · Grades 9–12 · Systems Thinking & Statistics

BottleneckForge

Almost everything you want — faster, more likely, done — runs through steps, and one step usually governs the whole. Read a real situation, predict what the numbers will do, then watch a deterministic engine work it out. No jargon, no lectures, nothing sent anywhere.

⏱️ Open the first lab 📝 Learn the concepts

Start here

Speed up one step A process has several steps. Someone speeds up one of them a lot — predict how much the WHOLE thing actually speeds up, then see the arithmetic (Amdahl’s law). Survival funnels Of 1,000 that enter — a drug pipeline, an audition, a job hunt — how many make it all the way through? Predict, then multiply the rates. How many shots Each try has some chance. Predict how many independent tries you need for a real chance of at least one hit — then compute it. Subscription funnels A subscription is a funnel too. Of 1,000 who start free, how many are still paying a year later? Predict, multiply the rates — and see who the funnel is designed for. You can always cancel. Concept practice 16 kits from “what a bottleneck is” to Amdahl’s law, base rates, the base-rate fallacy, attrition, and your own plan A.
Concept kits — 16 kits of bottleneck & base-rate reasoning

From “what a bottleneck is” to Amdahl’s law, base rates, attrition, and applying it to your own plan A. Progress stays on this device.

Kit 1: What a bottleneck is 25 questions Kit 2: Multi-stage processes 25 questions Kit 3: Amdahl's law (speed up one step) 25 questions Kit 4: Why the whole barely moves 25 questions Kit 5: Survival funnels 25 questions Kit 6: Multiplying stage rates 25 questions Kit 7: Base rates 25 questions Kit 8: The base-rate fallacy 25 questions Kit 9: How many shots for one hit (geometric) 25 questions Kit 10: Most trials fail (attrition) 25 questions Kit 11: Cost vs value across stages 25 questions Kit 12: Bottleneck in a startup, audition, or job hunt 25 questions Kit 13: Your own plan A 25 questions Kit 14: Optimizing the wrong step 25 questions Kit 15: Real case (structure is not a cure) 25 questions Kit 16: Capstone — find the real bottleneck 25 questions

Meet the cast — then teach one

Not mascots — everyday reasoners, each showing one idea in action. On the Teach page you help one of them read their own plan.

  • The Analyst — measures the whole pipeline, not the favourite step (the mentor)
  • Cap — hunts the slowest step — the one that caps the whole (the bottleneck)
  • Tally — counts survivors at each stage of a funnel (compounding attrition)
  • Reframe — asks whether one more push is even the right bottleneck to fix

🎓 Open the case coach

How it works

BottleneckForge trusts you — it’s about the reasoning, not memorizing terms, and a wrong prediction is just a place to learn. Every answer is worked out by a small deterministic engine, so the numbers are always exact. Your progress is saved only on this device: no accounts, nothing sent anywhere.

More ways in

More ways to play

Quiz Arena Flow Run Checkout Queue 100× Line Backup Subscriptions Is the posted wait right?

What next? Pick a door

Chosen from what this app is about. What you open is remembered on this device only.