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?

   • No problem, since a real gardener said it
   • The problem is that tomatoes are fruits
   • One plant, no comparison group, and the seller made the claim
   • 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?

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

3. 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.

4. 3.

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

   • Average the two studies' numbers together
   • Trust A, since it found an effect
   • Weigh B more, since it is larger and controlled, and test again
   • Throw out both studies, since studies that disagree are both wrong
5. 4.

   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?

   • Pick the lab whose result they like better
   • Repeat the test, compare methods and see which result replicates
   • Decide that yeast tests are not worth trusting, in this lab or any other
   • Keep Lab 1's result, since it was reported first
6. 5.

   A blog says mold grows faster in the fridge, based on one slice. Luz's class data on 20 slices show the opposite. Which should Luz trust?

   • The blog, since one clear slice is enough
   • The class data, since they use more slices and a clear comparison
   • The blog, since it is published online
   • Neither one, since mold grows far too randomly for anyone to study it

7. Mean height after 21 days (example data)

   Group	Plants	Mean height (cm)
   with plant food	10	21
   without plant food	10	15

8. 6.

   Milo's claim: "Plant food makes plants grow twice as tall." Which revised claim fits the data best?

   • Plant food had no effect on height
   • Plant food doubles the height of bean plants
   • Plant food helped these bean plants grow about 6 cm taller on average
   • Plant food makes any plant grow taller

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

   Seeds	Sprouted
   soaked overnight	18
   not soaked	11

10. 7.

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

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

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

    Patch	Visits
    purple	24
    yellow	15
    white	6

12. 8.

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

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

13. 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.

14. 9.

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

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

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