Materials
- Water
- Sugar
- Glass jar
- Spoon
- String or wooden stick
- Clothespin (optional)
- Food coloring (optional)
Procedure
- Heat about 1 cup of water until it is hot but not boiling.
- Slowly add sugar while stirring until no more dissolves (creating a saturated solution).
- Pour the sugar solution into a clean glass jar.
- Tie a string to a pencil or stick and suspend it in the jar so it doesn’t touch the bottom.
- Leave the jar undisturbed in a cool place for several days to allow crystals to grow.
- Optional: Add food coloring to the solution before growing crystals for colorful candy.
Choose Your Learning Level
Middle School
When sugar dissolves in water, it forms a solution. When the water can't hold any more sugar, crystals start to form and grow on the string. This is called crystallization.
Discussion Questions
- Why do crystals form on the string?
- What happens if you add too much sugar?
- How long do you think it takes for crystals to grow?
High School
Rock candy is formed through the process of crystallization, where a supersaturated sugar solution cools and sugar molecules arrange into a repeating pattern. Factors like temperature, saturation level, and impurities affect crystal growth.
Discussion Questions
- Explain the concept of supersaturation and how it relates to crystal formation.
- How do temperature changes influence the rate of crystallization?
- What role do impurities play in the crystal growth process?