Do plants need light? A 5th grade plant growth experiment
What it is: a 5th grade life science experiment where groups grow bean seedlings in two conditions, one in light and one in a dark box, and measure height and color for two weeks. Students run a fair test with one variable and use data to explain that plants need light to make food.
Time: about 20 minutes. Grade: 5th grade.
Materials: per group: 2 cups of soil with 3 bean seedlings each (sprouted the week before), a cardboard box to cover one cup, a ruler, water, and a data table.
- Ask: "What do plants need to grow? How could we test whether light is one of them?"
- Agree on what stays the same (soil, water, seeds, temperature) and what changes (light).
- Groups put one cup by a window and the other under a box in the same spot. They water both the same amount.
- Every 2 days, groups measure the tallest seedling in each cup and note its color.
- After 2 weeks, groups graph their data and explain the results. (Seedlings in the dark often grow tall, thin and pale, which surprises students.)
Safety: wash hands after handling soil, and check for allergies to plants or mold.
Differentiation: students who need support record color and height with a picture scale. Students who are ready research why dark-grown seedlings grow tall and pale. English learners can use the words variable, light, measure and pale.
Quick check: ask a student what they kept the same in the experiment and why it mattered.
Need it for another grade or subject? Ask us on the request page and our team will write it.
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About this resource
- Shared by
- @UpOnlyLearning · Curriculum team
- Posted
- Oct 29, 2026
- Type
- Lesson plan
- Grade
- Grades 3–5
- Subject
- Science
- Language
- English
- License
- Free for classroom, co-op and tutoring use. Please don't resell.