One of the coolest things in life, no matter how old you are, is watching a magic trick and being completely stupefied as to how it works. One of the most indulgent things in life, no matter how old you are, is chocolate. Today I’m combining the two, and using chocolate to demonstrate nature’s great magic trick – phase changes – solids to liquids to gases.
Usually I prep the kids with the ideas we’ll explore the next day before bedtime. I think that the terminology sinks in a little and the kids have time to start to question things so that we have a more fruitful discussion and experiment the next day. Last night I was telling Briana before bed that tomorrow we’d be making chocolate lollipops just like her friend Mitchell did for his 3rd birthday party favors and we’d be looking for how the chocolate can change, based on how hot we make it, from a solid piece of chocolate, to a liquid like hot chocolate, to a gas. Briana looks up at me and says, “Mommy, I don’t think I will like gas chocolate. I know who would like gas chocolate…the Mommy car [what she calls our minivan]! Yep, because the car would like a special treat gas sometimes.” I cracked up retelling that to my husband later, but at the time told her that it’s a different kind of gas and we’ll talk about it in the morning.
Incidentally, I have to thank Mitchell’s mom and my good friend, Elissa, for the idea for this blog. She told me that she and Mitchell had a great time making the chocolate lollipops and that she thought it would make a great lesson, for my blog, on liquids and solids.
The lesson part is broken into 3 sections:
Section 1- What are solids, liquids, and gases?
I sit the kids down after naptime and show them 3 clear cups. One has nothing in it. One has water in it. The last one has ice in it. I tell the kids that everything has 3 states – solid, liquid, and gas – and I point to the corresponding cup. I explain that gas is like the steam that comes up from the pot when I’m cooking dinner, but lots of times you can’t see the gas at all like in the cup. “The car can see gas and he likes it!” adds Bree. That’s a different kind of gas. The gas that the car drinks is actually a liquid.
A liquid moves around while solids are hard and stay in one shape. We talk about examples of things, mostly foods and drinks that are solids versus ones that are liquids. Once the kids understand what a solid and a liquid are, we move on to how one can become the other.
Section 2- How can a solid turn into a liquid?
Did you guys know that something that’s solid, like chocolate bars, can turn into a liquid? To turn a solid into a liquid, you have to make it get hotter. How can we make things hotter? “Put it in the oven.” says Bree. “Mouth.” says Abby, but she’s eyeing the chocolate on the table now so, while that’s accurate, I’m not sure that’s what she meant. I’ll show you a picture. It’s called a phase diagram. As you go to the right, it gets hotter. So a solid when it gets hotter turns into a liquid and then a gas. (Although that’s not always true because of the element of pressure, we’re going to assume a constant and average room pressure today. Also, since I’m adding side notes here, I introduced the phase diagram only because it’s the most straightforward visual of solids changing into liquids that I could think of. I don’t expect the kids to understand the phase diagrams meaning other than to have a reference to see what happens as you get hotter or colder pictorially.)
Section 3- How can a liquid turn into a solid?
You can go backwards on the phase diagram too. So the water when it gets really cold turns into… “Snow!” interrupts Briana. We’ve talked a lot about rainwater freezing into snow lately. (My ‘Revealing the Rain’ Blog has more about that.) Yes. Snow and also ice. When the water gets cold, it freezes and the water molecules get so close together that they can’t move around and change shape, so the water gets stuck in whatever form it’s in, like an ice cube. I demonstrate that last bit so that it makes more sense by pouring the liquid water into a 3 section baby plate and I tell the kids that the liquid takes the form of whatever it’s poured into. Then I put an ice cube into the plate and show them how the ice cube stays in the shape that it’s in. I check that the kids are still with me by asking Bree if that makes sense. She thinks for a minute and says, “The water gets cold and turns to ice and then it can’t move around anymore.”
I continue. Well, water is the liquid. When it gets cold, it turns into ice, which is the solid. All liquids, when they get cold enough, can turn into solids.
Today we’re going to make chocolate lollipops just like Mitchell did, and watch how the chocolate goes from a solid to a liquid when it gets hot and then back to a solid when it cools off again. So let’s make sure we understand what’s going to happen to our chocolate.
I explain further. When the chocolate is just at the same temperature of the room, it’s a solid chocolate. I point to the solid on the chart. When we put it in the microwave and make the temperature go up, it will turn into a liquid so we can pour it into our molds. More pointing. If we kept making the temperature go up, it would eventually become a gas, but we’re not doing that today. (Mostly because I have no idea what the flash point of chocolate is, but whatever it is it’s too hot to do with the kids, even if I could generate that kind of heat. Off the record, I can’t get the idea to keep heating the chocolate to see if I could create a chocolate gas out of my mind, but I’ll move on.)
Since the reverse works too, we will put our liquid chocolate in the refrigerator so the temperature goes down and it will turn back into a solid, but with the new flower shape of our mold. We’ll end up with…chocolate lollipops! I quiz the kids a lot about what happens as the temperature goes up. I think Abby is pretty much lost although she guesses solid, liquid, or gas randomly when I ask so I’ll take it as a success that she at least knows the words. Bree completely gets what’s going on.
With that I went and grabbed the chocolate making stuff and mass hysteria broke out at our house. I tried, in vain, to stick to not letting the kids eat any until we had made our lollipops. Instead we eat some of the chocolate first. Here’s Abby in chocolate bliss. For the record, she was allowed one (and ended up eating 3 by the end of the activity) - but she was not eating that whole bowl full of chocolate.
Then we sort all of the chips by color. We quiz Abby about what color each chip is and she’s starting to get her colors - purple, blue, green, and yellow at least. We count the number of chips in each color to practice our numbers.
I ask Bree, “What do we need to do get our solid chips to take the shape of the flower mold?” She matter-of-factly says, “Melt it.” I was so proud since I expected her to say make it a liquid at best or give me a blank stare worst case. So she picks light orange (her favorite color) to make first and I melt it in the microwave in 15 second increments and we stop after each times and look at the transition to liquid. Bree’s pretty excited now, and I’d like to think it was about the science, but it was probably about being one step closer to lollipops. I pour it into the molds with the sticks already placed in it and we observe how the liquid fills the mold. Just to reinforce the lesson, I put a solid chocolate chip in one of the molds and the kids laugh.
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| I tried to capture the guilty look Bree had when she "tested to see if it's still liquidy" by sticking her finger in one and licking it. |
The lollipops go in the refrigerator and 30 minutes later I have the happiest kids ever. The best part for me was that the kids kept asking if the chocolate was a solid again yet, which means that they understand the idea of the phase changes a little bit at least.
Just so you know, if you see me in the next couple of days I will be handing out homemade chocolate lollipops to get them out of our house.
Thanks for the idea, Elissa!
<3 Pedigreed Housewife
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