Exploring the Investigative World of Science

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The six moves of an investigation

Every scientific study is built from the same steps. Tap each term to see what it means and how it links to the next.

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The three big ideas

Observation is information you gather with your senses or with instruments — a thermometer, a measuring scale, a stopwatch. It must be about what actually happens, not what you hope happens.
A sharp observation sparks a question. The best scientific questions are testable — they can be answered by an experiment or by careful, repeated observation.
"Which colour is prettiest?" cannot be settled by science. "Does a moneyplant grow longer stems near a sunny window than in a dark corner?" can — that is the kind of question science begins with.
Keeping an honest record — drawings, tables, notes — turns scattered noticing into useful data you can return to.

Common mistake: jumping straight to "the answer". A useful investigation starts with a clear, narrow, testable question — not with the conclusion you wish for.

A hypothesis is a tentative, testable explanation that makes a prediction — for example, "Seeds soaked overnight will sprout sooner than dry seeds."
A variable is anything that can change. The independent variable is the one you change on purpose; the dependent variable is what you measure as a result; the controlled variables are everything you deliberately keep the same.
A fair test changes only one thing at a time. If two things change together, you cannot tell which one caused the result.
A control group gets no change, giving you something to compare the treated group against.

Worked example. Ravi wants to know if a plant food helps a chilli plant grow taller. How should he set it up?

Use two identical plants in identical pots and soil, in the same light, watered the same. Give plant food to one plant only (independent variable = plant food). Measure the height each week (dependent variable). Keep everything else the same (controlled). The plant with no food is the control.

Evidence is the data your test actually produces. A conclusion must be drawn from the evidence, even when it surprises you or goes against your hypothesis.
Repeat the test several times. A result others can reproduce is far more trustworthy than a single reading, which may carry error.
The scientific attitude is curiosity plus honesty: you report what you found, including failures, and you are willing to revise an idea when the evidence asks you to.
A hypothesis that is not supported is not a wasted experiment — it has taught you something true about the world.

Common mistake: "fixing" the data to match your guess. That is not science. The whole power of the method comes from letting honest evidence overrule your expectations.

Where you'll meet it

The method at work

Testing a new medicine

Before a medicine is approved, it is tested on two large groups: one gets the medicine, the other a harmless dummy (the control). Keeping the groups otherwise similar is what lets doctors trust that the medicine — and not chance — caused any improvement.

The school kitchen garden

Students wondering why one bed of spinach grows greener can run a fair test — same seeds and water, only the compost differs. Their tidy table of weekly heights is real evidence, exactly the way agricultural scientists compare crops.

Why the dosa didn't rise

A cook who changes only the soaking time of the batter — keeping flour, water and place the same — is running a controlled experiment without naming it. Everyday problem-solving uses the same fair-test logic as a laboratory.

Check yourself

Competency quiz

Modelled on the competency-based pattern — MCQ, assertion–reason and case studies, testing whether you can use the ideas, not just recall them.

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