Saltwater vs Freshwater Float Lab | Science Experiment
Saltwater vs Freshwater Float Lab | Science Experiment
You will test how salt changes buoyancy — then run an engineer-style Round 2 to see if you can reach the same floating changes using less salt. This is a shared lab for Fossil Scouts and Deep Blue Crew.
Shared Lab Round 1: Baseline Round 2: Salinity Engineer
What You Need
- 2 clear cups or bowls
- Water
- Salt
- 5 small test objects (safe shells, a cork, a plastic cap, a small stone, etc.)
- Spoon
Safety
- Adults handle sharp shells or teeth.
- Do not taste lab water.
- Clean the area after testing.
Required Action Steps
- Label one cup Fresh and one cup Salt.
- Fill both with the same amount of water.
- Test all 5 objects in the Fresh cup. Record what happens in your notebook.
- Round 1 — Baseline: Add 2 spoonfuls of salt to the Salt cup and stir until mostly dissolved.
- Test the same 5 objects in the Salt cup. Record what happens.
- Add one spoonful at a time until at least 2 objects float better, rise higher, or clearly change behavior.
- Record your total spoonful count as Round 1 Change Point.
- Round 2 — Salinity Engineer Challenge: Empty and refill the Salt cup with the same amount of water.
- Change one variable to try to reach a change with fewer spoonfuls: swap 1–2 objects or slightly reduce the water amount.
- Add salt again, one spoonful at a time, until 2 objects clearly change.
- Record your total spoonful count as Round 2 Change Point.
- Compare Round 1 and Round 2.