Unit 4 of 12 · Your choices · about 3 weeks

Decision-Making: How do I make a good choice when I can't know the outcome?

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This unit connects almost everything else in the course. Bias distorts decisions, procrastination is a decision about time, money is decisions about value, and geopolitics is decisions made by countries.

The key lesson most adults never learn: a good decision can have a bad outcome, and a bad decision can get lucky. Judge the decision by what you knew when you made it.

The framework

  1. Write it on the wall: Goal → Options → Benefits → Costs → Risks → Probability → Reversibility → Decision.
  2. Apply it to a real choice: "We have $100. Do we buy something now, save it, invest it, or start a small business?"
  3. Then a probability choice: "Tomorrow has a 30% chance of rain. Do we cancel the outing?"
  4. Then a trade-off: "Location A has a 70% chance of seeing the animal but poor scenery. Location B has a 30% chance but spectacular scenery. Where do we go?"

Core ideas

  • Separate the quality of a decision from the quality of its outcome.
  • Probability — how likely each outcome is — can be estimated even when it cannot be known.
  • Expected value = probability × outcome, summed across the possibilities.
  • Reversible decisions can be made fast; irreversible ones deserve more time.
  • Write down predictions so you can check your judgment later.

Activities

Marble bags

Put 7 red and 3 blue marbles in a bag. Red wins one candy, blue wins five. Is it worth a turn that costs two candies? Play 20 rounds and count — the youngest child discovers expected value without the name.

Family decision log

For one real decision a week, the family writes the options, the expected outcome and the confidence. A month later, review: was it a good decision, a good outcome, both, or neither?

Weather bets

Each day predict the chance of rain as a percentage before checking the forecast. Score predictions at the end of the unit.

One lesson, three outputs

Grades K–2 (ages 5–8)

Marble bags and "which bag would you pick from?" games. Talk about likely, unlikely, certain and impossible.

Grades 3–5 (ages 8–11)

Use the full framework on two real family decisions and write each one up. Express probabilities as fractions and percentages.

Grades 6–8 (ages 11–14)

Calculate expected value for the location problem and for a simple game, and explain when the higher expected value is still the wrong choice (risk you cannot afford to take).

The family question

Was that a bad decision, or a good decision with bad luck?

Thinking Journal prompt

What did I decide, what did I expect, and what happened? Would I make the same decision again with what I knew then?

Free resources