On Valentines Day, we made chocolate covered strawberries. I decided to turn it into a science project to teach my kids about phase transformations and melting points. (This was also a great project for gross and fine motor skill development as well as learning to follow instructions.)
Approximately 1 pound Strawberries (washed and dried) with the leaves, water (enough to boil in a small pot or double broiler), 16 ounces of melting chocolate (I used milk chocolate chips), and 4 ounces of white melting chocolate (I also used white chocolate chips).
1 Double Broiler (or you can use a metal or glass mixing bowl over a pot of boiling water), a mixing spoon to mix the chocolate as it melts, wax paper to place the strawberries after they are dipped in chocolate.
Step 1: Washing and drying the strawberries:
I place my strawberries in my sink to soak with cold water and about a 1/2 cup of white vinegar and 1/2 cup of baking soda for about 15 – 20 minutes. Then I gently scrub them with a cloth or scrub brush and rinse well. Next, I lay the strawberries out on a towel to dry completely (about 4 hours).
Measuring the ingredients:
We didn’t measure our strawberries, but one idea would be to use a kitchen scale for measuring out the strawberries and the chocolate. For older children, this would be a great a way to introduce conversions to various measurement scales. (We personally relied on the package quantities.)
Melting the chocolate:
When we melted the chocolate, we used a double broiler. I showed my daughters what the chips looked like (they are very familiar with them but I stressed that they were hard and cool) and, of course, I allowed them to taste them. I told them that this was the ‘solid’ form for chocolate and it felt cool at room temperature.
My 4 year old then poured them into the double broiler. I let her guess what would happen, “it’s going to melt, Mommy”, she said very confidently.
As we stirred the chocolate chips in the double broiler, she became more and more excited to see the chocolate melting before our eyes. I explained that the chocolate had reached it’s ‘melting point’. It was melting to a soft liquid and that this transition was called a ‘phase transformation’. My daughter easily recognized the liquid was hot when I allowed her to put chocolate on one strawberry felt the heat from the pot.
WARNING: The chocolate will be HOT. Be sure that your child is ready to do this on their own without burning themselves.
If you have a cooking thermometer, you may want to consider placing it into the chocolate as it melts and let your child look at or record the temperature of the chocolate as it melts.
We continued to dip the strawberries in the double broiler (until all sides were covered in chocolate), then laid them on wax paper lined pans to cool. I asked my daughter what she thought might happen as they cool. She agreed that the chocolate would harden around the strawberries into a solid again (another phase transformation).
White Chocolate Drizzle:
I melted the white chocolate in a microwave safe bowl in the microwave. (If you do this, do it gradually and stir it between heating cycles to prevent the chocolate from burning.) I allowed my 4 year old to experiment with the technique on this. This also helps with fine and gross motor development.
Let me know if you try this out! We had a lot of fun with this one. It is a very simple project and more lessons can be added depending on the age of your children. Let me know what you think in the comments below or at MomgineeringtheFuture@gmail.com.