Scientific method
The core concepts behind every fair test — how to ask a testable question, write a hypothesis, and tell your variables apart.
The scientific method
The six-step loop scientists use to turn a question into evidence, and why real research rarely runs in a straight line.
Hypothesis
How to turn a question into a testable if-then-because prediction, with a worked example and what makes a hypothesis testable.
Independent vs dependent
How to tell the independent variable from the dependent variable in any experiment, with a worked example and common mix-ups.
Controlled variables
Why every fair test needs a list of controlled variables, and what goes wrong in an experiment when one gets left out.
Control vs experimental
Understand control vs experimental groups, choose an appropriate baseline, assign samples fairly, and see how group comparisons support or limit causal claims.
Qualitative vs quantitative
How to sort a lab observation into qualitative (described) or quantitative (measured), with side-by-side examples from real labs.
Observation vs inference
How to tell a direct observation from an inference (an educated guess based on that observation), with examples students mix up most.
Confounding variable
What a confounding variable is, how it's different from a controlled variable, and a worked example of one ruining a fair test.
Placebo effect
Why experiments involving people need a placebo group, and how that group helps separate a real effect from a psychological one.
Peer review
The steps a scientific study goes through before publication, and why peer review — while not perfect — raises the bar for credibility.
Correlation vs. causation
Why two variables moving together isn't proof one causes the other, with a classic example and how experiments get closer to real causation.
Hypothesis examples
Worked hypothesis examples from biology, chemistry, physics, and environmental science, all following the same testable format.
Experimental design
The decisions that make up a solid experimental design — variables, controls, trials, and bias — and the most common ways weak designs fail.
Theory vs. law
Why a theory doesn't 'graduate' into a law, what each one actually describes, and real examples of both from across science.