Tell a hypothesis, a theory and a law apart
Grade 9 Science Worksheet - Building Confidence
Circle the best answer.
Read this first
Sorting card with three boxes
Hypothesis, Theory, Law. Statement to sort: "Energy cannot be created or destroyed in a living cell, only changed from one form to another."
Ari sorts a statement from a biology poster. Which box does it go in, and why?
- A theory: it explains why energy changes form inside a cell
- A theory: it covers more evidence than a law, so it ranks above one
- A hypothesis: nobody has tested it yet, so it is only an idea
- A law: it states a pattern found in every measurement, without saying why
Use this
Lab plan line. "If warmth speeds up the reactions inside bean seeds, then seeds at 25 °C should sprout in fewer days than seeds at 15 °C."
Bo reads a line in a lab plan. Which kind of statement is it?
- A theory: it explains how seeds sprout, based on many tests
- A law: it states a pattern that holds each time seeds are tested
- A hypothesis: it explains why warmth should matter to the seeds
- A prediction: a result expected if the hypothesis about warmth is right
Notes line. "In the second generation, 705 plants had violet flowers and 224 had white flowers." Esme reads a line from Mendel's pea notes. Which kind of statement is it?
- A law: it states the pattern found in each pea cross
- A hypothesis: it offers a reason for the white flowers
- A theory: it explains how flower color is passed on
- An observation: a recorded result, with no explanation attached
Jun checks four sentences for the word hypothesis. Which uses it the science way?
- Brighter light may make plants taller because leaves make more sugar, which three lamps can test
- A hypothesis is any guess, so a test is not needed to make one
- Once a hypothesis passes two tests it is renamed a theory
- A hypothesis is a fact that has been proven many times, so it needs no further tests of any kind
Kira checks four sentences for the word theory. Which uses it the science way?
- My theory about the late bus is a guess that has not been checked yet, so a theory is a hunch
- A theory becomes a law after enough tests have been run on it
- A theory is a statement of a pattern, with no explanation of why
- Cell theory is a well-tested explanation that predicts what new tissue samples will show
Luz checks four sentences for the word law. Which uses it the science way?
- A law explains why mass is conserved in a reaction, so a law does exactly the same job as a theory
- The law of conservation of mass describes what happens to mass in every reaction, not why
- A law is a theory that has finally collected enough proof to be promoted
- A science law is a rule that stays fixed, whatever we later find
Milo's friend says evolution is "just a theory", so it is a guess. Which reply fits science?
- A theory is an explanation backed by many lines of evidence, such as fossils and DNA
- Right, theories are hunches that scientists have not tested
- Right, an idea like that stays a guess until enough tests finally turn it into a proper law
- Evolution is proven, so it cannot be changed by new evidence
Noah finishes a test of a hypothesis, and the results match the prediction. Which sentence is best science writing?
- The results show the hypothesis was a wild guess that happened to work out well this time
- The results support the hypothesis but cannot prove it, and more tests could change that
- The results turn the hypothesis into a theory, since it passed a test
- The results prove the hypothesis, so it is now a fact for good
Pia compares a school rule with a science law. Which sentence about science laws is right?
- A science law is a theory that has passed so many tests that it was finally promoted to a law
- A science law is a rule that nothing in nature is allowed to break
- A science law explains why a pattern happens, as a theory does
- A science law describes a pattern in nature and can be revised when exceptions turn up
Four lines from Mendel's pea notes (real data, Mendel 1866)
line entry A Round seeds may hide the wrinkled form B 5,474 seeds were round and 1,850 were wrinkled C Each egg or pollen cell gets one copy of each gene D Genes are carried on chromosomes Tala reads Mendel's pea notes. Which line is the observation, not a hypothesis, law or theory?
- Line D: genes are carried on chromosomes
- Line A: round seeds may hide the wrinkled form
- Line C: each egg or pollen cell gets one copy of each gene
- Line B: the counts of round and wrinkled seeds
