The math, science, computing, and habits every STEM career is built on.

STEM Foundations: The Universal Skill Stack

Science is a way of asking questions so the world can answer them. The loop:

1. **Observe** something and ask a question.
2. **Hypothesize** — a specific, testable guess.
3. **Experiment** — change one thing (the *variable*) while keeping everything else the same, so you know what caused any change.
4. **Measure** the result and compare to your prediction.
5. **Revise** and repeat.

The key idea is the *fair test*: if you change five things at once, you can't tell which one mattered. Controlling variables is what separates evidence from a hunch.

Turn a question into a testable hypothesis and a fair experiment.

The scientific method and experiments

No measurement is perfect. A ruler, a scale, a sensor — each has a limit to how precise it is. Mature STEM thinking means reporting that **uncertainty** instead of pretending it isn't there.

- **Precision vs. accuracy.** Precise = repeatable. Accurate = close to the true value. You can be precisely wrong (a scale that always reads 2 kg high).
- **Repeat measurements.** One reading can be a fluke; several reveal the real pattern.
- **Evidence over opinion.** A claim backed by reproducible measurements beats a confident voice every time.

This is why scientists write down *how* they measured, not just the number — so others can check.

Every measurement has error — good scientists report it.

Measurement, uncertainty, and evidence

The scientific method, measurement, uncertainty, and evidence.