The Scientific Method
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50 free The Scientific Method trivia questions with answers — science & nature quiz, new questions added Oct 2026.
The scientific method is less a recipe than a habit of mind: ask a question, make a prediction that could turn out wrong, test it fairly, and let other people check the result. It is how a ship's surgeon, a Viennese doctor and an accidental mould each changed medicine, and how some celebrated discoveries were later shown to be mistakes or outright fakes. This quiz follows what a science class covers and goes a little further: the steps of an investigation, what to change, what to measure and what to keep the same, how to read results without fooling yourself, and the vocabulary that trips people up. It also visits the famous experiments and the thinkers, from the ancient world to the twentieth century, who worked out how reliable answers are won. The questions run from elementary and middle school basics to a set of advanced ones for high school and college students, and every answer comes with a short explanation, so it works for revision, as a classroom starter or as a printable multiple choice quiz with answers.
30 of 50 questions with answers and explanations. Play the quiz
Q 01Which drug did Alexander Fleming discover in 1928 after mould spoiled a culture plate left out over his holiday?
Penicillin
Penicillin began as an accident: Fleming came back from a family holiday to find bacteria destroyed around a stray fungus, and is said to have remarked, "That's funny."
Q 02Apollo 15's David Scott dropped a falcon feather on the Moon alongside which object to show both fall equally fast?
Hammer
The hammer and the feather hit the lunar dust together, because the Moon has almost no atmosphere to drag on the lighter object.
Q 03Clever Hans, who amazed 1900s Germany by tapping out answers to arithmetic problems, was what kind of animal?
Horse
The horse was not doing sums: in 1907 psychologist Oskar Pfungst showed Hans was reacting to involuntary cues in his trainer's body language.
Q 04James Lind ran one of the first clinical trials in 1747, giving sailors oranges and lemons to treat which disease?
Scurvy
Scurvy was the target: Lind put twelve sick sailors on the same diet in six pairs, and the pair given oranges and a lemon were all but well after six days, when the fruit ran out.
Q 05In 1847 Ignaz Semmelweis slashed deaths in a Vienna maternity clinic by ordering doctors to do what?
Wash their hands
Wash their hands, he insisted, in chlorinated lime: mortality fell from 18% to under 2%, yet offended colleagues mocked him and he died in an asylum in 1865.
Q 06What name, from the Latin for 'I shall be pleasing', is given to a dummy treatment such as a sugar pill?
Placebo
Placebo tablets contain nothing active, so clinical trials use them to check how much of a new medicine's benefit comes from the drug itself.
Q 07In everyday speech a theory is just a hunch, but in science the word describes what?
A well-supported explanation
A well-supported explanation is the scientific sense: evolution, plate tectonics and the germ theory of disease have each been tested repeatedly and are backed by corroborating evidence.
Q 08Russian physiologist Ivan Pavlov discovered classical conditioning while studying digestion in which animals?
Dogs
Dogs in his laboratory began to drool at the mere presence of the technician who fed them, which led Pavlov to pair food with the tick of a metronome.
Q 09What do scientists call the one factor they deliberately change in an experiment, such as the dose in a drug trial?
Independent variable
Independent variable is the term, because the experimenter sets its value freely; whatever is then measured, such as how severe the symptoms are, depends on it.
Q 10Which garden crop did the Augustinian friar Gregor Mendel breed by the thousands to uncover the rules of heredity?
Peas
Peas gave Mendel seven clear traits to track, from seed shape to flower colour; he grew some 28,000 plants, yet the work went unrecognised for more than three decades.
Q 11In a vaccine trial, what are the volunteers called who receive a saltwater injection instead of the real shot?
Control group
Control group volunteers get no active treatment, so any difference between them and the vaccinated volunteers can be credited to the vaccine itself.
Q 12Which process, also known as refereeing, has experts in the same field check a study before a journal publishes it?
Peer review
Peer review was not yet routine in 1905: Albert Einstein's four famous papers of that year went into print on the say-so of the journal's editors, with no outside referees.
Q 13Which trial design, tried in an 1835 Nuremberg salt test, keeps both patients and researchers unaware of who gets what?
Double-blind
Q 21Which French chemist used swan-necked flasks of boiled liquid to help overturn the old idea of spontaneous generation?
Louis Pasteur
Louis Pasteur relied on the curved neck to let air in while trapping airborne particles, so the liquid stayed free of microbes; his work on the question won the Alhumbert Prize in 1862.
Q 22Which Italian physician covered jars of meat with fine gauze to show that maggots come from the eggs of flies?
Francesco Redi
Francesco Redi left a second set of jars open for comparison: maggots appeared only where flies could land, undermining the belief that rotting meat breeds them by itself.
Q 23John Snow plotted deaths around London's Broad Street water pump in 1854 to trace the source of which disease?
Double-blind trials withhold that information until the study is over, so neither a patient's hopes nor a researcher's expectations can colour the results.
Q 14An educated guess about nature only counts as a scientific hypothesis if it has which property?
It is testable
It is testable: a hypothesis must make a prediction about reality that an experiment or observation can check and that other researchers can reproduce.
Q 15Plants get different doses of fertilizer but identical pots and sunlight: which is the study's dependent variable?
Plant height
Plant height is the outcome that depends on the treatment, so it is what gets measured, while pots and sunlight are held constant so that they cannot affect the result.
Q 16Which word describes observations recorded as numbers, such as a temperature of 25 degrees, rather than as descriptions?
Quantitative
Quantitative comes from quantity: these observations have numerical values that can be analysed with statistics, unlike properties that are observed but not measured.
Q 17Which check, failed by many published psychology studies in the 2010s, repeats a study to see whether its results hold?
Replication
Replication exposed a problem in 2015: of 97 psychology studies that had reported significant effects, only 36% produced one again when a large project repeated them.
Q 18Ice cream sales and drownings both rise in summer, a textbook case of which statistical link often mistaken for cause?
Correlation
Correlation only shows that two things move together: hot weather drives both, since people buy more ice cream and also swim more, so neither one causes the other.
Q 19Which English champion of the experimental method is said to have caught a fatal chill while stuffing a hen with snow?
Francis Bacon
Francis Bacon died of pneumonia in 1626; John Aubrey's account has him stopping on the road to Highgate to try whether snow could preserve meat as salt does.
Q 20Which Italian, called the father of the scientific method, found four moons of Jupiter with his own telescope?
Galileo Galilei
Galileo Galilei watched the 'stars' beside Jupiter change position night after night in January 1610 and concluded that they were orbiting the planet, not Earth.
Cholera
Cholera deaths clustered around the pump, and the pattern persuaded the parish to remove its handle; workers at the nearby brewery, notably, never caught the disease.
Q 24Which Greek librarian of Alexandria worked out the size of the Earth by comparing noon shadows in two Egyptian cities?
Eratosthenes
Eratosthenes knew the midsummer Sun shone straight down a well in Syene while rods in Alexandria still cast shadows, and scaled that angle up over the 5,000 stadia between them.
Q 25Arthur Eddington checked Einstein's general relativity in 1919 by photographing star positions during which event?
A total solar eclipse
A total solar eclipse let expeditions to the island of Príncipe and to Brazil measure how far starlight was deflected as it passed the darkened Sun, as Einstein had predicted.
Q 26Which Vienna-born philosopher argued in The Logic of Scientific Discovery that a scientific claim must be falsifiable?
Karl Popper
Karl Popper pointed out that no number of white swans can prove that all swans are white, yet a single black one refutes it, so a claim earns its keep by risking disproof.
Q 27Which rule of thumb, named after a 14th-century English friar, favours the explanation with the fewest assumptions?
Occam's razor
Occam's razor honours William of Ockham, although he never used its best-known wording, "Entities must not be multiplied beyond necessity".
Q 28Which 'missing link' fossil of 1912 turned out, four decades later, to be a human skull with an orangutan's jaw?
Piltdown Man
Piltdown Man was not definitively exposed until 1953; a 2016 study pinned the hoax on its finder, amateur archaeologist Charles Dawson, apparently seeking recognition.
Q 29Which 1989 claim by chemists Fleischmann and Pons collapsed when other labs could not reproduce their tabletop results?
Cold fusion
Cold fusion promised nuclear energy from a jar of heavy water at room temperature, but by late 1989 most scientists considered the claim dead.
Q 30Which French thinker's 1637 Discourse on the Method contains the famous line 'I think, therefore I am'?
René Descartes
René Descartes wrote the line in French, as "Je pense, donc je suis"; the Latin version, "Cogito, ergo sum", appeared seven years later in another of his books.