I can usually spot them in an experiment but I mix up which name goes with which.
Accepted answer
Tie each to what the experimenter *does* with it.
- **Independent variable** — the one you deliberately **change**. It's independent of the outcome; you chose it. Goes on the **x-axis**.
- **Dependent variable** — the one you **measure**. Its value *depends* on the independent variable. Goes on the **y-axis**.
- **Control variables** — everything else you deliberately **keep the same**.
Example: testing how temperature affects how fast sugar dissolves. Independent = water temperature (you set it). Dependent = time to dissolve (you measure it). Controls = sugar mass, volume of water, stirring rate, grain size.
Controls are what make the result mean anything. If you changed the temperature *and* stirred the hot one harder, a faster dissolve proves nothing — you couldn't say which change caused it. That's the reasoning behind "a fair test": exactly one variable changes at a time.