Students set up several seedling pots to test one need at a time by comparing a control with three treatments: no water, salt water, and no light. They track growth over time using simple height markings to decide which conditions help plants stay healthy.

1. Gather identical seedlings (or seeds), pots with soil, labels, popsticks, marker, measuring jug, salt, water, and a dark cupboard or box.
2. Set four groups with 2 seedlings each: Control, No Water, No Light, Salt Water.
3. Keep everything the same for all groups except the one variable being tested.
4. Water Control on schedule; place in normal light.
5. Do not water No Water after initial planting.
6. Place No Light in darkness but water on the Control schedule.
7. Water Salt Water with a mild salt solution (about 1 teaspoon in 250 ml water) on the Control schedule.
8. Record height weekly and note color, wilting, or leaf changes.

What Happened to Our Plants? | Science Project for Kids - SciShow Kids:

📄 Investigating plant growth - Primary Connections: https://primaryconnections.org.au/teaching-sequences/year-1/survive-and-thrive/lesson-2-investigating-plant-growth

• Add a crowding group by planting many seedlings together.
• Test weaker and stronger salt solutions.
• Graph weekly class averages for each treatment.

• Wash hands after handling soil and solutions; do not ingest.
• Label salt solution clearly; avoid using near food areas.
• Wipe spills promptly; use small water containers for students.
• Bag and bin salty soil; do not return it to gardens.

• Why is a control needed? (It shows normal growth for comparison.)
• Which single factor changes in each treatment? (Water, light, or salinity.)
• What signs show water stress? (Wilting, slowed growth.)
• What happens without light? (Pale, weak growth; no photosynthesis.)
• How does salt reduce growth? (It makes water uptake harder and damages cells.)