Tell a hypothesis, a theory and a law apart
Grade 9 Science Worksheet - Building Confidence
Circle the best answer.
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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 prediction: a result expected if the hypothesis about warmth is right
- A hypothesis: it explains why warmth should matter to the seeds
Jun checks four sentences for the word hypothesis. Which uses it the science way?
- Once a hypothesis passes two tests it is renamed a theory
- Brighter light may make plants taller because leaves make more sugar, which three lamps can test
- A hypothesis is a fact that has been proven many times, so it needs no further tests of any kind
- A hypothesis is any guess, so a test is not needed to make one
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 is a statement of a pattern, with no explanation of why
- A theory becomes a law after enough tests have been run on it
- 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 science law is a rule that stays fixed, whatever we later find
- A law is a theory that has finally collected enough proof to be promoted
- The law of conservation of mass describes what happens to mass in every reaction, not why
- A law explains why mass is conserved in a reaction, so a law does exactly the same job as a theory
Milo's friend says evolution is "just a theory", so it is a guess. Which reply fits science?
- Right, an idea like that stays a guess until enough tests finally turn it into a proper law
- Right, theories are hunches that scientists have not tested
- Evolution is proven, so it cannot be changed by new evidence
- A theory is an explanation backed by many lines of evidence, such as fossils and DNA
Noah finishes a test of a hypothesis, and the results match the prediction. Which sentence is best science writing?
- The results support the hypothesis but cannot prove it, and more tests could change that
- The results show the hypothesis was a wild guess that happened to work out well this time
- 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 describes a pattern in nature and can be revised when exceptions turn up
- 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
Three ideas on a biology poster (example data)
idea what it says idea 1 All living things are made of cells, and new cells come from existing cells idea 2 Each egg or pollen cell gets one of the plant's two copies of a gene idea 3 Seeds may sprout sooner in warm soil because warmth speeds their reactions Ren reads a poster with three ideas. Which labels fit, in order?
- Idea 1 is a hypothesis, idea 2 is a law and idea 3 is a theory
- Idea 1 is a theory, idea 2 is a law and idea 3 is a hypothesis
- Idea 1 is a theory, idea 2 is a hypothesis and idea 3 is a law
- Idea 1 is a law, idea 2 is a theory and idea 3 is a hypothesis
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 C: each egg or pollen cell gets one copy of each gene
- Line B: the counts of round and wrinkled seeds
- Line D: genes are carried on chromosomes
- Line A: round seeds may hide the wrinkled form
Zee bakes bread. Which statement is a hypothesis that a test could check?
- Warmth may speed up yeast because its reactions run faster when warm
- Living things, yeast included, are made of cells
- Any wild guess counts as a hypothesis, like "yeast likes jazz", since a guess needs no reasons
- The dough in the warm kitchen rose 3 cm in an hour