Judge a biology claim: evidence, reasoning and reliable sources

Grade 9 Science Worksheet - Challenge Me

Circle the best answer.

1. 1.

   An ad says, "A gardener's tomato grew 40% bigger with our spray!" What is the biggest problem with this claim, Ari asks?

   • One plant, no comparison group, and the seller made the claim
   • No problem, since a real gardener said it
   • The problem is that tomatoes are fruits
   • No problem, since 40% is a big gain
2. 2.

   A study found 3 plants with music grew 2 cm taller than 3 plants without. The claim: "Music makes plants grow." What is the problem, Bo asks?

   • No problem, since the music plants were taller
   • Too few plants, so a 2 cm gap could be chance
   • Plants cannot hear, so no test was needed
   • Music has no effect on any living thing
3. 3.

   A survey found more frogs and more insects in gardens near a pond. Esme's friend claims the frogs attract the insects. What is the problem?

   • There were fewer frogs near the pond
   • It is a link from a survey; the pond could explain both
   • Frogs attract insects, since both are higher
   • Insects attract the frogs, which settles the question for good

4. Read this first

   Use this

   Two studies (invented examples). Study A: 10 plants, no control group, found that compost helped. Study B: 200 plants with a control group found no difference.

5. 4.

   Jun finds two compost studies that disagree. What is the best conclusion?

   • Trust A, since it found an effect
   • Throw out both studies, since studies that disagree are both wrong
   • Weigh B more, since it is larger and controlled, and test again
   • Average the two studies' numbers together
6. 5.

   Two labs ran the same yeast test. Lab 1 found more gas in warm water; Lab 2 found no difference. What should scientists do, Kira asks?

   • Repeat the test, compare methods and see which result replicates
   • Pick the lab whose result they like better
   • Decide that yeast tests are not worth trusting, in this lab or any other
   • Keep Lab 1's result, since it was reported first

7. Bean seeds sprouted by day 5, 20 seeds each (example data)

   Seeds	Sprouted
   soaked overnight	18
   not soaked	11

8. 6.

   Noah's claim: "Soaking makes seeds sprout." Which revised claim fits the data best?

   • By day 5, more soaked bean seeds had sprouted than unsoaked ones
   • Soaked seeds sprouted sooner because the water made them heavier
   • Unsoaked seeds cannot sprout
   • Soaking makes any seed sprout within 5 days

9. Bee visits to three flower patches, 30-minute count (example data)

   Patch	Visits
   purple	24
   yellow	15
   white	6

10. 7.

    Pia's claim: "Bees prefer purple because purple flowers have more nectar." Which revised claim fits the data best?

    • Bees visited white flowers most
    • Bees avoid white flowers everywhere
    • Purple flowers have more nectar, so bees prefer them
    • In this count, bees visited purple flowers most; the reason was not tested

11. Use this

    Two sources (invented examples). A: a shop page selling a plant spray shows 2 plants: sprayed 30 cm, unsprayed 20 cm. B: a university test of 60 plants found both groups averaged 22 cm.

12. 8.

    Ren compares a shop page and a university test of the same plant spray. Which conclusion is best?

    • The two count equally, since both show plants
    • The spray works, since 30 cm beats 20 cm
    • The spray works, since the shop's photo clearly shows a taller sprayed plant
    • The larger test, from a source with nothing to sell, shows no effect

13. Use this

    Two sources (invented examples). A: a government science page, reviewed in 2025, with references, says plants need light to make their food. B: an unsigned 2008 blog says plants given sugar water need no light.

14. 9.

    Tala finds two pages about what plants need. Which is more reliable, and why?

    • B, since it has been online longer
    • A, since it is dated, reviewed and backed by references
    • Neither, since both are websites
    • B, since its idea is more surprising and new than the government page

15. Use this

    Two sources (invented examples). A: a peer-reviewed study of 300 seeds found salt water lowered sprouting. B: a comment says, "My seeds sprouted fine in salty soil!"

16. 10.

    Zee reads a study and a comment about salt and seeds. Which should Zee trust more?

    • The comment, since one success disproves the study
    • The comment, since it is a real person's own experience with salty soil
    • Both equally, since each one has a point
    • The study, since it tested many seeds and experts checked it