Chemical and physical changes in matter are a classic part of elementary science curriculum. Ice, liquid, and steam, for example, are frequently used to demonstrate the way water can change forms.
But that doesn’t mean you need to stop there. Take some butter, sugar, and a curious fourth grade chef, add a dose of heat on your stove and keep track of its effects with a candy thermometer. In twenty minutes or less, you can have some mouthwatering toffee — blue ribbon candy science! Here’s how.
What You Need:
- 1 cup butter
- 1 cup white sugar
- 1/3 cup dark brown sugar
- 1/2 teaspoon baking soda
- 1/3 cup chopped almonds or hazelnuts (optional)
- Candy thermometer
- Deep saucepan (sugar syrup can burn if it spatters, so don’t use a shallow pan)
- Lightly greased jelly roll pan, or other large flat pan with edges
What You Do:
- First, invite your young scientist to check out some basic chemistry: pour a few teaspoons of plain white sugar onto a dark piece of paper, and take a good look with a magnifying glass or even better, a microscope. Now put it a little bowl and mix it with a pat of your butter. Invite your child to taste just a little — feel the crystals on your tongue?
- Set your experiment aside. Now it's time to start cooking! Add 1 cup of sugar and 1 cup of butter to a sturdy saucepan with tall sides. Fasten your candy thermometer firmly to the side of your pan (these thermometers normally come with a clamp).
- Begin boiling the mixure over low heat, stirring constantly. Parents, take note: fourth graders can do this, but supervise very carefully. If the mix starts to spatter, it’s time for a grownup to take over while young scientists observe.
- To make toffee, you need to heat the sugar mixture to 280°, stirring constantly. What’s going on? You’re dissolving a large quantity of sugar into butter, and cooking them into a super-hot syrup that will then harden into one buttery, crystalline candy. At this temperature, the mix will make a ball if it’s dropped into ice water. Do be careful here—this stuff is hot and even a small spatter can cause a burn!
- Now you’re ready for your delicious experiment results. Working quickly, remove the pan from heat, stir in ½ teaspoon of baking soda, and add nuts if you like them. Then pour the whole mix onto the greased baking sheet. Scrape the pot out thoroughly and then let the whole batch cool. Give it about an hour to be safe, and then break it apart. Get ready for kitchen science that’s positively irresistible!
Julie Williams, M.A. Education, taught middle and high school History and English for seventeen years. Since then, she has volunteered in elementary classrooms while raising her two sons and earning a master's in school administration. She has also been a leader in her local PTA.