The Chocolate Lab

Activity 1: Speed Melting

Description: Who can melt their chocolate fastest? Each participant will receive one square of a chocolate bar and will experiment with how to melt it without tools. They can rub their hands together to generate heat. They can breathe on the chocolate. They can hold it close to their bodies. They can hold it on their tongue. But figuring out their own technique is all up to them! We will discuss why heat melts chocolate, note how long it takes to melt, how melting temperatures compare to our body temperatures, and what happens in the chocolate’s chemicals when it melts.

Supplies:

• 4 regular-sized Hershey bars (Any solid chocolate bar can be used, but the thickness of Hershey bars make them ideal for this experiment.
• Paper towels/baby wipes

Instructions:

When starting this activity, engage the children in conversation about their favorite kinds of chocolate, then ask them if they’ve ever left chocolate in a hot car. What happens to it? Hand each child a piece of chocolate and tell them that their job is to soften/melt the chocolate. Ask them how they can make heat with their bodies in order to melt the chocolate quickly. If they are not sure, ask what they do when they’re cold. Do they make fists to keep their fingers warm? Do they cross their arms to keep their bodies warm? Explain that chocolate is made of a solid substance from the cocoa bean called cocoa butter. Cocoa butter melts easily, so it only takes a bit of heat to soften or melt completely. Cocoa butter, and therefore the chocolate, start melting at only 86 degrees. That’s the temperature of a warm, sunny day, isn’t it? Our bodies have a regular temperature of 98.6 degrees, which is warmer than the temperature that chocolate melts at. That’s why chocolate gets soft when we hold it and melts completely into a liquid if it is near or in a lot of heat.

If more conversation/discussion is needed while the students are melting their chocolate, ask them if added ingredients in candy bars, like crisped rice, nuts, or caramel melt like the chocolate does? After hearing the above explanation of why chocolate melts, they may be able to explain that rice, nuts, etc., don’t have cocoa butter in them to melt. (Time permitting, this would be a great time to mention that other ingredients like butter melt easily, too.) Allow the kids to eat their chocolate pieces, then wash their hands or use baby wipes to clean up.

Activity 2: DIY Chocolates

Description: Participants will create their own chocolate candies by spooning melted chocolate into candy molds, thus learning how quickly chocolate solidifies when it cools. When each child is finished, a staff member will place the mold in the refrigerator/freezer until set (approximately until the end of the Large Group Activity).

Supplies:

•     Chocolate discs
•     Candy molds
•     Bowls
•     Spoons
•     Paper towels/baby wipes
•     Baggies
•     Marker
•     Masking tape

Instructions: While the Ice Breaker activity is happening, have an assistant melt the chocolate discs and separate the chocolate into four bowls. When ready to start this activity, have each child select a chocolate mold and label with it by writing their name on a strip of masking tape. Set the bowls of chocolate in front of them (they will have to share) and have them take turns stirring it and noting its consistency. Instruct them to spoon chocolate into their molds and note how the chocolate changes as they stir, spoon and move it. Ask if they know why the chocolate is changing. It was heated to a liquid in the microwave, but as it cools, it is hardening back into a solid. Explain that their chocolate candies will hold the shapes they chose because the chocolate will cool and form in the mold. Ask if they have any ideas how they can make the chocolate harden faster. Place the molds in the refrigerator/freezer to set. After the large group activity, remove them and have the kids flip the molds over onto paper towels. Ask the kids to tell you why the chocolate set into shapes and see if they remember the specific melting temperatures you mentioned earlier. Hand out baggies for the children to write their names on and put their chocolates in to take home.

Activity 3: Float or Sink Candy Bars

Description: Density determines if something will sink or float in water. Candy bars filled with airy ingredients, like nougat and wafers, will float while those packed with nuts, caramel and fruit, will sink because there is not enough air to compensate for the weight of the ingredients. This activity will give participants a chance to test out the weight of each candy bar, make predictions about what they think will happen and track the results.

Supplies:

• Treat-sized candy bars (different varieties like Snickers, Hershey bars, Kit Kat, Three Musketeers, Peppermint Patties, etc.)
• Large, deep, transparent container (fish tank, plastic bin, etc.)
• Poster board/easel
• Scotch tape
• Scissors

Instructions: Give each child a candy bar and explain: “A Kit Kat bar has a lot of empty space in between the chocolate and the wafer cookies. Those pockets contain air, which help keep the density low so the bar floats. The same is true for the 3 Musketeers bar. The nougat center has a lot of tiny air bubbles whipped into it, creating little pockets of air to keep the density low so it floats on the surface of the water, too. Like a Three Musketeers, the Snickers has a whipped nougat center but the pockets of air it contains aren’t enough to overcome the higher density of the peanuts, caramel, and chocolate. Hershey’s bars have the same problem. There are a few air pockets in the solid chocolate, but not enough to keep the bar from sinking” (Spangler, 2015).

Have each child in turn open their candy bar, gauge its weight, make a prediction, and drop it into the water. If it sinks, note how quickly or slowly it does so. When the result has been determined, have the child tape their wrapper to the Float or Sink side of the board. If there are a greater number of participants than there are types of candy bars, have some of the children break their candy bar in half to test with. They can cut their wrappers in half to tape to the graph.

When activity is complete, have children compare the types of candy bars that floated or sunk. Reiterate the concept of density and, time permitting, discuss other foods with which they might want to continue this experiment.

*Idea borrowed from Steve Spangler (Spangler, 2015).

Activity 4: Design Your Own Wrappers!

Description: Participants can let their sweet tooth rule their imaginations as they imagine a brand-new candy bar. With provided supplies, they can design a wrapper for their creation. When they finish and show it to library staff, participants will receive a Hershey bar in which to wrap their wrapper.

Supplies:

• Hershey bars
• White copy paper
• Hershey bar wrapper template
• Markers/crayons/colored pencils
• Scotch tape

Instructions: Set out pencils, markers, colored pencils, crayons, and copies of the candy wrapper template on tables. If doing this activity as part of the Chocolate Lab, encourage participants to get creative with ideas for new candy bars. Remind them to come up with a catchy name that will make people want to buy their product. Let them know that there is a surprise waiting for them when they finish and show a library staff member their creation.