Judge a biology claim: evidence, reasoning and reliable sources
Grade 9 Science Worksheet
Circle the best answer.
Ari's claim: "Compost helps bean plants grow taller." Which evidence supports it best?
- A gardener on a video says compost helped
- 20 plants with compost averaged 25 cm; 20 without averaged 17 cm, same light and water
- Compost is made from old leaves
- One plant given compost grew to 25 cm
Bo's claim: "Warm rooms make bread mold appear sooner." Which evidence supports it best?
- Slices at 22 °C showed mold in 5 days on average; at 4 °C, in 12 days
- A cooking blog with no author or date says warm kitchens grow mold faster
- One slice left out on a warm day grew mold
- Mold is a kind of fungus
Esme's claim: "Bees in this garden visit purple flowers more than white ones." Which evidence supports it best?
- A garden shop near the school sells more purple flower seeds than white ones
- One bee landed on a purple flower
- Purple is a popular color
- Counts on 10 mornings: purple averaged 24 visits, white averaged 6
Read this first
Bean seedlings after 14 days (example data)
Lamp Plants Mean height (cm) bright 10 18 dim 10 10 Jun's claim: bright light helped the seedlings grow taller. Which reasoning links the evidence to the claim?
- The plants averaged 18 cm and 10 cm
- Leaves use light to make sugar, which the plant uses to grow
- The bright lamp cost more money, so it must have been the better lamp
- Taller plants look healthier
Days until mold was first seen, 5 slices each (example data)
Where kept Temperature Mean days fridge 4 °C 12 counter 22 °C 5 Luz's claim: mold grows faster on warm bread. Which reasoning links the evidence to the claim?
- Counter slices showed mold in 5 days
- Any warm bread will grow mold, wherever it is kept in the house
- Mold is alive, and warmth speeds up the reactions in its cells
- Warm bread smells more like mold
In a survey of 10 yards, yards with more earthworms had taller grass. Noah asks whether earthworms make grass taller. Which answer is best?
- Earthworms cause taller grass, since both rise together
- The survey shows a link, not a cause; a controlled test is needed
- Taller grass must be bringing the earthworms
- The data show no link between the two
In Pia's garden, plants given rainwater grew taller than plants given circle water. The rainwater plants were also in sunnier beds. Which conclusion is best?
- Rainwater is the cause, since those plants were taller
- Sunlight has no effect on plant growth
- Tap water harms any plant it touches, so gardens should skip it
- Sunlight also differed, so rainwater may not be the cause
Use this
Two sources (invented examples). A: a university extension page with references, last reviewed in 2025. B: a shop page selling "super seed powder", with no references.
Ren compares two sources about seed sprouting. Which is more reliable, and why?
- A, since it cites evidence and has nothing to sell
- B, since it has the most excited reviews
- Both equally, since both are online
- B, since a store that sells the powder knows its own product well
Use this
Two sources (invented examples). A: a peer-reviewed journal article that tested 200 tomato plants. B: a video of one gardener's tomato plant.
Tala compares two sources about plant growth. Which is more reliable, and why?
- B, since the gardener has grown tomatoes for years and knows them well
- A, since journal articles cannot be wrong
- A, since experts checked its methods and it tested many plants
- B, since you can see the plant yourself
Use this
Two sources (invented examples). A: a government agency page with references, last reviewed in 2024. B: a page from a group that sells garden products, with no date.
Zee compares two pages about soil. Which is more reliable, and why?
- Neither, since no website can be trusted
- A, since it is dated, referenced and not selling anything
- B, since it is shorter and easier to read
- B, since a group that sells garden products has no reason to be biased