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Today is my kid’s first day of school. Our summer felt long, but now that school is starting we’re all saying it was too short! It’s all about perspective, and hopefully with this experiment we can teach our kids that the wait for these rock candy treats is worth it when they are enjoying their sugar-filled rock candy!
Making rock candy requires a lot of patience. First, waiting for the sugar to dissolve in the hot water, then waiting for the saturated solution to cool. Then it’s another 2 week wait for the rock candy to form. But while my kids were enjoying their rock candy I asked them if it was worth the wait, and they both gave me a resounding, “Yes!!!”
MATERIALS:
- 2 cups water
- Saucepan
- 6 cups sugar
- Measuring cup
- Spoon
- Wooden candy sticks
- Food coloring
- Flavoring (optional – we used vanilla extract)
- 4 pint size mason jars
PROCEDURE:
- Prep the wooden candy sticks by soaking in water for 15-60 min (we soaked for ~30 minutes about the same time it took us to heat the water and dissolve the sugar)
2. Roll the wet wooden sticks in sugar, coating the bottom 3/4 of the stick, then set aside to let dry completely.
3. Pour 2 cups water into the saucepan, and begin to heat over medium heat.
4. Add 1 cup of sugar, stirring until completely dissolved.
5. Continue adding sugar one cup at a time until it will no longer dissolve (the water will look cloudy at this point). It will be approximately 3:1 sugar to water when fully saturated. For example, we used 3 cups of water and 9 cups of sugar. This made A LOT of solution. I would recommend starting with 2 cups of water and ~6 cups sugar.
6. Bring the saturated solution to a boil, then allow to simmer for ~10 mins
7. Remove from heat and allow to cool.
8. Meanwhile, add a few drops of food coloring and any flavoring, if using it, to the bottom of the jars. We added a different color to each jar and about a teaspoon of vanilla extract to each jar.
9. Pour the liquid into the jars, and stir to mix in the color and flavoring. Allow the liquid to continue cooling to room temperature.
10. Place one sugar-coated stick in each jar, and use a clothespin to hold each stick in the center of the jar, and at least 1/2” from the bottom of the jar.
11. Set the jars aside in a place where they won’t be disturbed for 2 weeks. You can observe the jars as the crystals grow, but do not move them.
12. After 2 weeks, remove the sticks from the liquid. You may have to break the hard layer of crystals on the surface of the jar. You should have fully formed rock candy crystals!
13. Enjoy eating the sugar crystals you grew!
STEAM CONCEPTS LEARNED:
- Science: Supersaturated solution – By adding heat we were able to add more sugar than is normally soluble in water creating a 3:1 supersaturated solution.
- Science: Crystallization – As the supersaturated solution cools, crystals begin to form in two ways. First the sugar will come out of the solution forming precipitate, which sticks to the seed crystals on the stick. Second, as time elapses water will evaporate out of the solution making it even more supersaturated, so more sugar will precipitate out and join the growing crystals on the stick.
- Math: Practice measurement and counting while adding ingredients
Making the rock candy solution took us half the day, starting by making the syrup in the morning, and it was finally cool to room temperature by the afternoon. This is a great activity if you’re doing virtual learning or homeschooling. You can start it before school starts. At lunch the solution will be cooled enough to transfer to the jars.
My kids spent some time examining the crystals that grew on the sticks before eating the treat. They were very fascinated that the huge sugar crystals grew from the liquid solution they had made weeks before.
These treats are pure sugar, so I was hesitant to make them with my kids knowing they will eat at least 1 or two each. But at least I know exactly what is in this candy, since we made it ourselves. It’s just water, sugar, vanilla extract and food coloring. As long as we aren’t doing this too often, I’m ok with my kids enjoying this home-made and educational treat.
Have you ever made rock candy before? Do you plan to try this activity with your kids?
