Last week our boys teamed up to create a science project for their school’s annual science fair, the study of seed crystals. Although participating in the science fair was optional for their grade, both boys were so excited to try an experiment of their own to show their teachers, principal, and school friends.
For our science project, we created a twist on the homemade rock candy recipe we did the week before. Instead of coating all the skewers with sugar before adding them to the water/sugar solution like we did in the rock candy craft, we only coated 1/2 of our skewers to see if the sugar-coated skewers helped the crystals grow faster or not.
We used a standard tri-fold for our study of seed crystals science project display and included detailed directions and observations, lots of photographs, and we also brought our solution filled jars to display for everyone to see. The boys even brought their colored rock candy from the week before to show everyone what they did.
Studying the science of seed crystals growth and whether they promote faster growth of sugar crystals is a fun and simple experiment to introduce children to science.
The Study Of Seed Crystals Growth
Materials and Equipment
- Stove Top
- Pot Holders
- Mixing Spoon
- Wooden skewers (be sure to cut the pointed tips off if needed.)
- Mason Jars
- Clothes Pins
- Granulate White Sugar
- Measuring tool
- Project Journal
3 Parts Sugar to 1 Part Water
(Note: We used pint mason jars which hold 2 cups of liquid each. You will only need 1 cup of water for each pint jar because once you add the sugar the liquid volume will double.)
In this project, we will investigate how the presence of seed crystals changes the growth rate of rock candy.
- Separate your wooden skewers (remember to cut off the pointed tips) into two sets.
- Soak one set of skewers in water for 5 minutes. Leave the second set aside and do nothing to it.
- Pour a small amount of sugar on a plate and roll the wet wooden skewers in the sugar to coat. These wooden skewers are your seeded (sugar-coated) skewers.
- Lay the skewers on a plate to dry.
- In your large pot, bring water to a soft rolling boil on the stove top. (Remember, your liquid volume will double so be sure you have enough room in your pot.) Add sugar, one cup at a time and stir slowly with your mixing spoon until the sugar has completely dissolved. Repeat until all your sugar has been added. The mixture will double in volume and be very sticky.
- Let the solution come back to a rolling boil then remove the water/sugar solution from the heat. Let the mixture set for 15 minutes to cool. (Optional: Preheat the glass jars. This will make sure that you are not adding your hot sugar-water solution to a cold jar, which would result in a dramatic temperature change that might make small crystals form along the glass.)
- After the water/sugar solution has cooled, carefully pour the hot solution into the mason jars. Caution: Be extremely careful when pouring the sugar-water solution; it is hot and sticky and will burn if spilled on your skin.
- Using pot holders, move the jars with the water/sugar solution to a location where they can be left undisturbed for one week.
- Gently lower the seeded wooden skewers into the solution in 1/2 of the jars, and gently lower the non-seeded wooden skewers into the solution in the rest of the jars keeping all the skewers as close to the center as possible and not allowing them to touch the bottom of the jar.
- Attach a clothes pin to the skewer just above the rim of the jar to hold your skewer in place.
Observations and Measurements
Look at your jars once a day and record the changes you see in your project journal. Are there crystals growing? Which skewers have more crystals: the ones that were seeded or the ones that weren’t?
On the last day, remove the skewers from the jar and take measurements of your crystals. Measure the width at the widest point and the length. Did the seeded crystals make a difference in the size of rock candy you grew?
Once you have recorded all of the data for you study of seed crystals experiment, you can enjoy your hard work by eating the rock candy!
What did you find? Did your experiment work as expected?
How does the study of seed crystals work?
When the water and sugar were mixed, we made a super saturated solution. The water could only hold the sugar as long as both were very hot. As the water cooled the sugar came out of the solution and transformed back into sugar crystals on your skewer. The skewer (and sometimes the glass itself) act as a seed that the sugar crystals start to grow on. With some luck and patience, you will end up with a tasty scientific treat! Enjoy!
How Our Seed Crystals Developed
Day 1 (Start of Experiment)
Make It Your Own
Don’t forget to have a little fun with your children and make a second batch to experiment with. Try adding different colors and flavors as we did here.