Dissolving substances in water is one of the most immediately observable chemical concepts in everyday life. Salt disappears. Sand sinks to the bottom. Sugar vanishes. Flour makes a cloudy suspension. Each material behaves differently, and children can observe the differences directly, make predictions before testing, and check whether their predictions were correct. This is a complete scientific investigation using only a glass of water and kitchen materials.

Materials to Test

• Salt (dissolves completely)
• Sugar (dissolves completely)
• Sand (settles to the bottom)
• Flour (creates a cloudy suspension)
• Baking soda (dissolves and produces gas with acid)
• Oil (floats on top, does not dissolve)
• Cornstarch (makes a non-Newtonian fluid — weird!
• Pebbles (sink, do not dissolve)

The Experiment Process

1. Set up identical clear glasses of room-temperature water.
2. Before adding each substance, ask: "Do you think this will dissolve? Will it disappear, sink, or float?"
3. Add one teaspoon of each substance to its glass. Stir for 30 seconds.
4. Observe: Did it disappear? Is the water cloudy? Did it sink?
5. Record results on a simple chart: Dissolves / Sinks / Floats / Clouds.

Frequently Asked Questions

What is the difference between dissolving and mixing?

When something dissolves (like salt), the particles break apart into individual molecules that spread evenly through the water — you cannot see them separately, and the water appears clear. When something mixes but doesn't dissolve (like flour), the particles remain intact but suspended — the water appears cloudy. When something doesn't mix at all (like oil), it separates out into its own layer. These distinctions are accessible to preschoolers through observation even before the vocabulary fully develops.

Related science: Sink or Float | Paper Towel Absorbency | Kitchen Science