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?
- Compost is made from old leaves
- 20 plants with compost averaged 25 cm; 20 without averaged 17 cm, same light and water
- One plant given compost grew to 25 cm
- A gardener on a video says compost helped
Esme's claim: "Bees in this garden visit purple flowers more than white ones." Which evidence supports it best?
- One bee landed on a purple flower
- A garden shop near the school sells more purple flower seeds than white ones
- 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
- The bright lamp cost more money, so it must have been the better lamp
- Leaves use light to make sugar, which the plant uses to grow
- Taller plants look healthier
Kira's claim: warm water helped yeast make more gas. Mean gas was 8 mL at 20 °C and 22 mL at 40 °C. Which reasoning fits?
- Yeast just prefers warm water
- Warmth speeds up the reactions yeast uses to break down sugar
- The warm bottles made 22 mL of gas
- Warm water looks bubblier and fizzier, so the yeast must be working harder
In a survey of 6 school gardens, gardens with more bird feeders had more flowers. Milo's friend says feeders make flowers bloom. Which response is best?
- They rise together, but another factor, like care or sunlight, could explain both
- The feeders cause the blooms, since both go up
- More feeders went with fewer flowers
- The survey settles that feeders help flowers
In a survey of 10 yards, yards with more earthworms had taller grass. Noah asks whether earthworms make grass taller. Which answer is best?
- The data show no link between the two
- The survey shows a link, not a cause; a controlled test is needed
- Earthworms cause taller grass, since both rise together
- Taller grass must be bringing the earthworms
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?
- Tap water harms any plant it touches, so gardens should skip it
- Sunlight has no effect on plant growth
- Sunlight also differed, so rainwater may not be the cause
- Rainwater is the cause, since those plants were taller
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?
- Both equally, since both are online
- B, since a store that sells the powder knows its own product well
- A, since it cites evidence and has nothing to sell
- B, since it has the most excited reviews
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?
- A, since journal articles cannot be wrong
- B, since the gardener has grown tomatoes for years and knows them well
- 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?
- B, since a group that sells garden products has no reason to be biased
- B, since it is shorter and easier to read
- A, since it is dated, referenced and not selling anything
- Neither, since no website can be trusted