Science activity
Mixture vs Solution Lab
Mix things together and see what happens! Some things disappear in water (like sugar) and some don't (like sand). Can you separate them back apart?
Materials and setup
- clear cups
- water
- sugar
- salt
- sand
- coffee filters
- spoons
- shallow dish
- iron filings (optional)
- magnet
- thermometer
- kitchen scale
How this changes by age
Pre-K (ages 3–4)
Mix things together and see what happens! Some things disappear in water (like sugar) and some don't (like sand). Can you separate them back apart?
Steps
- Fill 3 clear cups with water.
- In cup 1, add a spoonful of sugar and stir. 'Where did the sugar go? It disappeared! It dissolved.'
- In cup 2, add a spoonful of sand and stir. 'The sand didn't disappear! It sank to the bottom.'
- In cup 3, mix small beads, pasta, and buttons together. 'This is a mixture — you can see all the pieces.'
- Separate the mixture in cup 3 by picking out each item. 'We can separate a mixture easily!'
- Tell a grown-up one thing that surprised you.
Learning objectives
- Observe that some materials dissolve in water and others do not
- Understand the difference between dissolving and mixing
- Practice separating a simple mixture by hand
Kindergarten (ages 5–6)
Explore mixtures and solutions by mixing, dissolving, and separating. Learn that solutions look clear because the substance breaks into tiny invisible pieces, while mixtures still show separate parts.
Steps
- Make a solution: dissolve sugar in warm water. Stir until it disappears. Taste it — the sugar is still there even though you cannot see it!
- Make a mixture: mix sand and salt together in a bowl. Can you see both parts? That is a mixture.
- Separate the mixture: add water to dissolve the salt, then pour through a coffee filter. The sand stays in the filter, the salt water goes through.
- Recover the salt: put the salt water in a shallow dish in a sunny spot. Wait for the water to evaporate. Salt crystals appear!
- Sort 8 items into two groups: things that dissolve (sugar, salt, drink mix) and things that don't (sand, pepper, rice).
- Tell a grown-up one thing that surprised you.
Learning objectives
- Distinguish between mixtures (visible parts) and solutions (dissolved, clear)
- Separate a mixture using filtration and evaporation
- Predict which substances will dissolve in water
Early elementary (ages 6–8)
Investigate mixtures and solutions systematically: test solubility of various substances, measure how much dissolves at different temperatures, learn separation techniques, and recover dissolved substances.
Steps
- Research: a solution forms when a solute dissolves in a solvent. The solute breaks into particles too small to see. A mixture keeps its separate parts visible.
- Test solubility: try dissolving 10 substances in water (sugar, salt, flour, sand, baking soda, oil, pepper, drink mix, chalk dust, vinegar). Record: dissolves (solution), partially dissolves, or does not dissolve (mixture).
- Temperature experiment: dissolve as much sugar as possible in cold water, warm water, and hot water (same volume each). Measure how many spoonfuls dissolve in each. Does temperature affect solubility?
- Learn 4 separation techniques: (1) Filtration — pour sandy water through a filter. (2) Evaporation — evaporate salt water to recover salt. (3) Magnetism — pull iron filings from sand with a magnet. (4) Sieving — separate rice from flour with a strainer.
- Challenge: separate a complex mixture of sand, salt, iron filings, and small pebbles using the techniques you learned. Plan your steps before starting.
- Write a lab report: explain the difference between mixtures and solutions, present your solubility data, temperature graph, and describe how you separated the complex mixture.
- In one sentence, tell a parent or sibling what surprised you today.
Learning objectives
- Explain the difference between mixtures and solutions at a particle level
- Measure how temperature affects the solubility of a substance
- Apply multiple separation techniques to isolate components of a complex mixture
Upper elementary (ages 8–10)
Conduct advanced mixture and solution chemistry: create solubility curves, explore saturated and supersaturated solutions, investigate colloidal mixtures, and design a multi-step separation challenge.
Steps
- Create a solubility curve: dissolve as much sugar as possible in 100mL of water at 5 different temperatures (cold, cool, room temp, warm, hot). Record the mass dissolved at each temperature. Graph temperature vs. solubility.
- Make a supersaturated solution: dissolve as much sugar as possible in very hot water, then let it cool slowly WITHOUT disturbing it. Drop in a single sugar crystal — watch rapid crystallization occur! Explain why this happens (the solution holds more than it normally could).
- Investigate colloids: mixtures where particles are suspended, not dissolved. Make examples: milk (fat in water), fog (water in air), gelatin (liquid in solid). How are colloids different from solutions and mixtures? Test with the Tyndall effect (shine a laser pointer through — colloids scatter the beam, true solutions don't).
- Design a multi-step separation challenge: give a friend a mixture of salt, sand, iron filings, small pebbles, and oil in water. They must plan and execute a separation strategy to isolate all five components.
- Research chromatography: separate the colors in markers by placing a dot on a coffee filter and adding drops of water. Different pigments travel at different speeds, separating the ink into its component colors.
- Write a chemistry paper: cover solution theory, your solubility curve data and analysis, supersaturation crystallization, colloids and the Tyndall effect, and your chromatography results.
- In one sentence, tell a parent or sibling what surprised you today.
Learning objectives
- Create and interpret a solubility curve showing temperature-dependent solubility
- Demonstrate supersaturation and explain the crystallization process
- Distinguish between solutions, colloids, and suspensions using physical tests
Safety and evidence note
Read the full activity before beginning. An adult should supervise tools, heat, food, outdoor work, movement, and experiments as appropriate. Completion records that the activity was done; the child’s explanation, work sample, photo, or demonstration is stronger evidence of learning than a completion check alone.
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