Doing science well means using a small set of precise words the way every scientist does — hypothesis, variable, control, evidence. Vocabulary here is not decoration; it is the tool. A student who can tell an observation from an inference, or an independent variable from a dependent one, can design a fair test, read a graph honestly, and defend a finding. Muddle the words and the thinking muddles with them.
Keep a running vocabulary page at the back of the lab notebook; add to it every time a new process word appears. When you use one of these words, use it precisely — say what you mean by “variable” or “uncertainty” before you write it down. Using the word correctly is what makes it yours.
| Term | Plain meaning | Example & what it tells you |
|---|---|---|
| Hypothesis | a testable prediction, with a reason | “Raise the ramp and the car rolls farther, because…” — it can be proven wrong. |
| Prediction | what you expect one test to show | “This tablet fizzes faster in warm water” — the hypothesis aimed at one experiment. |
| Variable | anything that can change | ramp height, water temperature, light — name them first. |
| Independent variable | the thing you change | the ramp’s height — the cause you are testing. |
| Dependent variable | the thing you measure | how far the car rolls — the effect. |
| Controlled variable | what you keep the same | same car, same floor, same push — keeps it fair. |
| Control group | a trial with no change | seedlings on plain water — your baseline for comparison. |
| Fair test | change one, hold the rest | one fold on the paper airplane — the idea of Unit 04. |
| Observation | what you sense and record | “the ice took 6 minutes to melt” — neutral, no guessing. |
| Inference | an explanation from observations | “it melted faster because the room was warm” — goes beyond the data. |
| Qualitative | in words, not numbers | “the water turned cloudy” — what a number can’t capture. |
| Term | Plain meaning | Example & what it tells you |
|---|---|---|
| Quantitative | a number with units | “14.2 cm in 3.0 s” — what you graph and compare. |
| Significant figures | the digits you can trust | 12.4 cm (three) vs 12 cm (two) — how precise the tool was. |
| Precision | repeats close to each other | five trials near 3.1 s — but a ruler can be precisely wrong. |
| Accuracy | close to the true value | 3.1 s when the truth is 3.1 s — about the truth, not agreement. |
| Uncertainty | how far a reading might be off | “10.0 ± 0.2 s” — every measurement has it. |
| Error | random scatters; systematic shifts | shaky hand vs mis-zeroed scale — the kind tells you the fix. |
| Mean & range | the average and the spread | mean 3.0 s, range 2.8–3.2 s — an honest summary. |
| Outlier | a point far from the rest | 9 s among five near 3 s — investigate, don’t delete. |
| Replication | run the same test repeatedly | five drops, not one — separates a result from a fluke. |
Don’t swallow the table in one sitting. Keep this page open during reading and lab; each time you use one of these words, use it precisely, then check yourself. The habit turns the vocabulary into the set of tools you think with — which is the whole point of a course about how to do science.