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
- 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
Bo's claim: "Warm rooms make bread mold appear sooner." Which evidence supports it best?
- Mold is a kind of fungus
- 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
Esme's claim: "Bees in this garden visit purple flowers more than white ones." Which evidence supports it best?
- Counts on 10 mornings: purple averaged 24 visits, white averaged 6
- 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
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 bright lamp cost more money, so it must have been the better lamp
- The plants averaged 18 cm and 10 cm
- 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?
- Warmth speeds up the reactions yeast uses to break down sugar
- Yeast just prefers warm water
- Warm water looks bubblier and fizzier, so the yeast must be working harder
- The warm bottles made 22 mL of gas
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 survey settles that feeders help flowers
- The feeders cause the blooms, since both go up
- More feeders went with fewer 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?
- Earthworms cause taller grass, since both rise together
- The data show no link between the two
- Taller grass must be bringing the earthworms
- The survey shows a link, not a cause; a controlled test is needed
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?
- 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
- Tap water harms any plant it touches, so gardens should skip it
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?
- B, since a store that sells the powder knows its own product well
- A, since it cites evidence and has nothing to sell
- Both equally, since both are online
- B, since it has the most excited reviews
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