(light-hearted music) - Hi, welcome back to "Teaching in Room 9," the region's largest classroom.

I'm Briana Rodgers, and I teach in the Mehlville School District.

Today, I'm gonna be teaching science for second graders, but as always, all learners are welcome.

I'm so glad that you're back again for another week of our summer camp learning.

And this week's theme... (fingers snap) The beach.

Today, I'm gonna take you all with me to the beach to learn about some science that happens when you're outdoors.

Okay, maybe we're not really going to the beach, but we're gonna talk about some great science and we can use our imaginations, right?

Today, we're gonna be making observations about solids and liquids and how they change when heat is added to them.

And when I was thinking about going to the beach, it got me excited.

And I started thinking about how I always love packing a picnic whenever I go.

But it's always challenging to think about where do I need to put my snacks to bring them to the beach?

Because at some times, I'm able to just throw them in my backpack or my beach bag.

And other times, I have to bring an insulated cooler like this to make sure that they don't melt.

I'm gonna show you a video.

And I want you to think about what do you know about states of matter.

Solids, liquids and gases, what do you notice?

What do you wonder?

♪ Let's go (funky music) ♪ Wait for the drums ♪ Uh ♪ Uh ♪ Ta, ta ♪ Night, night ♪ That night, I do crazy things at night ♪ ♪ Trapping What you just saw in that video was a sped up video of a very popular beach snack, a Popsicle.

They're cold.

They're great to have when it's warm out and the sun is shining.

But what did you notice was happening to the Popsicle?

The surface that the Popsicle was sitting on had heat.

So the Popsicle was heating up, and you might've noticed that it was changing.

It looked much different in a puddle on the surface than it did when it started off as an actual Popsicle.

That's something you may have noticed whenever you go outside with a Popsicle, or maybe even ice cream, you've noticed it start to drip down your hand or it gets a little bit messy.

We call that melting.

You've probably seen it happen before.

But did you know that when something is melting, it's actually changing a state of matter.

Today, we're gonna talk about these different states of matter.

And what does it mean to change a state of matter?

So our Popsicle here, before it was put on that tray, was a solid.

A solid is something that keeps its shape.

So you're probably pretty familiar with a lot of different solids.

This marker is a solid, because it has a very specific shape and size.

This computer mouse is a solid, because again, it has a very definite shape, size.

It doesn't change very much.

So our Popsicle, to start off with, was a solid.

But when we added heat to it, it turned into a liquid.

A liquid is something like water that doesn't keep it shape.

It actually keeps the shape of the container that it's in.

So, our solid Popsicle, when heat was added to it, it turned into a liquid.

That actually happens with a lot of different things, not just Popsicles.

In states of matter, they can change between different types of matter.

So our solid, when we added heat, it turned into a liquid, Can you think of anything else that when you add heat to it, it starts out as I solid, and adds heat and turns into a liquid?

I was thinking about ice cubes, ice cream cones.

A lot of the food that you probably keep in your freezer at home, when you take it out, heat is being added to it.

So it might start to melt.

Let's watch one more video where we can see a solid melting into a liquid.

In that video, you saw ice which is a solid melt or change into a liquid.

So just to remind you all that a solid is something that has a definite shape.

So our Popsicle or our ice cube, they always stay that shape unless they change into a liquid.

Now, a liquid doesn't have a definite shape.

It's gonna be shaped like it's container.

So, in the videos we watched, it was flat and spread out across the surface.

But if you pour water into a cup or a bowl, it's gonna take the shape of the cup or the bowl because it doesn't hold its own shape.

It flows, it's fluid.

So when our solid turns into a liquid, we call it melting.

And what we just watched was that we were adding heat.

So when we add heat to a solid, it turns to a liquid.

But you might notice on my chart here, I have an arrow going the opposite way as well because we can turn a liquid into a solid.

You might have ice cubes at your house, and you might know that those actually started out as liquid water.

And a lot of times we take the water and we put it in our freezer so that we can freeze it.

Freezing is turning a liquid into a solid, so the opposite of what we just watched.

And so, some people might think that we're adding cold or we're adding it to the freezer to make it a solid.

But what we're actually doing is we're taking away heat.

So you'll see the little minus sign here.

So when we're taking heat from a liquid, it turns into a solid.

And when we add heat to that solid it turns back to a liquid.

So when we're putting food or a liquid into our freezer, we're actually taking heat away from it to turn it back into a solid.

So let's go back to thinking about our picnic basket that we might be bringing to the beach with us.

We have to think about what foods are we bringing with us that might change from a solid to a liquid when heat is added.

Because if you've been to the beach before or just outside in St. Louis in the summer, you know that the sun can get really hot outside.

So just like that Popsicle melted, there might be some other foods that we bring to the beach that might melt as well.

So we have to be sure that we put them somewhere that will stop the heat from getting in like an insulated cooler.

Let's look at some different snacks and see if we can make some predictions on which ones might melt when heat is added to them.

Let's take a look at a couple of different snacks that I like to bring along to the beach with me.

So one of my favorite things to eat are these veggie chips.

They're so good.

And they're sort of like potato chips, but they're made with different vegetables instead of potatoes.

So I'm wondering, would I be able to throw these in my beach bag and bring them to the beach, or will they melt?

Do I need to be able to put them in an insulated cooler bag?

The other snack that I love to bring along to the beach is chocolate-covered pretzels.

So good.

Sweet and salty are a great combination.

So again, I'm wondering, with chocolate-covered pretzels, can I throw them in my beach bag or will they melt and do I need to keep them in an insulated cooler?

I want you to think about what you might know about these two things.

Chocolate-covered pretzels, veggie chips, very similar to potato chips, and make some predictions.

Do you think they'll melt?

Or do you think that they can be kept outside of a cooler when we head to the beach?

I'm gonna give you a second to think, and then we're gonna use this plate over here to observe and see what happens.

So there's heat coming off of this right now, which is a little bit different than when you're at the beach, because the sun is what's creating the heat when you're at the beach.

But because we're indoors right now, and we're not actually at the beach with the sun shining, we're gonna use this to demonstrate that heat being added to these two solids.

So what we want to look for is to see, are these solids gonna turn into a liquid when we add heat?

First, I'll add some of these veggie chips.

What do you notice happening?

Do you see any change?

I don't see much happening yet, but let's leave them there and add our other snack of our chocolate-covered pretzels and see what happens.

What do you notice?

Do you see anything changing?

We'll let those both sit there for just a minute while we think about how might we know if things are going to melt when they're in the heat.

Well, when we're looking at solids, we can sometimes make observations to decide whether we think that it's something that might melt.

So, think about the things that you keep in your freezer.

A lot of times, if you take those out, they're going to melt because they need to be cold to stay at a solid.

Other things can stay solid at room temperature.

So, sometimes you can bring them out in the heat and they'll stay a solid.

Sometimes things that we keep at room temperature will melt.

But it's important to think about what temperature do we typically keep that item at.

So, but something that we keep in the fridge or the freezer, there's a chance that it might melt or at least get pretty warm and maybe not be very tasty.

Let's go back and look at our two snacks and see if anything's changed.

Our veggie chips over here still look pretty similar.

They still look pretty edible to me.

So it doesn't seem like the heat's doing very much to them, especially not melting them.

Let's check out the chocolate-covered pretzels.

There's definitely some change happening there.

You can see, it looks very shiny and glossy.

That chocolate on top of the pretzels is melting off.

You might even notice some of that steam coming off, which is another change of state.

It's a liquid turning into a gas.

So, thinking about our two snacks that we had today, we definitely would want to keep our chocolate-covered pretzels in the cooler so that they don't melt.

So it's definitely important that we make some observations or do some research before we grab all of our snacks to head to the beach.

We want to make sure that if they're gonna melt when heat is added to them, that we bring them in a cooler.

So, speaking of melting, do you remember that Popsicle I showed you earlier?

It's not much of a Popsicle anymore.

It melted, and I didn't have to add a lot of heat to it, but this room just isn't cold enough to keep it a solid.

So it melted into a liquid.

But do you think I can turn it back into a solid?

On our chart up here, we showed that when heat is added to a solid, it changes to a liquid.

But I also showed you that when heat is taken away from a liquid, it turns back into a solid.

One way to take heat away from something is to either remove it from the heat source.

So if you're out in the sun you could bring it back inside to let it turn back into a solid.

Or for some things, like our Popsicle here, we would probably have to put it back into the freezer for it to turn back into a solid.

But there's a lot of other ways that we could turn liquids back into a solid by taking heat away.

So, I want you guys to do a fun activity with me today to demonstrate how we can turn liquids into a yummy, solid snack.

Before we start our next activity, let's take a brain break and test your knowledge of solids and liquids.

I'm gonna show you some pictures of objects commonly found on or around the beach.

If the object shown is a solid, I want you to jump up and do jumping jacks.

If the object is a liquid, you're gonna drop to the ground and hop like a frog.

Let's see how you do.

First one is a beach ball.

If you think a beach ball is a solid, you're gonna jump up and do jumping jacks.

If you think it's a liquid, you're gonna drop down and hop like a frog.

Next is water.

Do you think water is a solid or a liquid?

If it's a solid, you're gonna do jumping jacks.

If it's a liquid, you're gonna hop like a frog.

Next is flip-flops.

Are flip-flops a solid or a liquid?

How about watermelon?

I love watermelon.

Is watermelon a solid?

If so, you're gonna do jumping jacks.

And if you think it's a liquid, you're gonna hop like a frog.

All right, last one, sunscreen.

Now, this one's tricky.

Don't think about the container, but the sunscreen inside of it, is it a solid or a liquid?

All right, let's see how you did.

The beach ball, the watermelon, and the sandals were a solid, great job.

And the two items that were liquid were the water and the sunscreen.

You guys did awesome.

To help demonstrate how liquids can turn back into a solid, we're actually gonna use a recipe from our friend Ruff Ruffman.

So, we're gonna make one of my favorite snacks, especially when I'm going to the beach, which is ice cream.

So, I'm gonna share with you how to make this ice cream with ingredients you might even already have at home.

But you can also look up the ice cream shake recipe on the PBS website as well.

So, for our ingredients today, we're going to need 1/2 a cup of whole milk or cream, a tablespoon of sugar, which I've already measured out in here.

A teaspoon of vanilla extract, two cups of ice, and 1/4 cup of salt, along with two Ziploc bags.

One is a gallon-sized bag.

The other is a quart-sized bag.

You're gonna want to make sure that they zip really tight at the top because we're actually gonna shake this ice cream to get it to turn from a liquid into a solid.

So we're gonna start with our smaller bag here.

And this is the part that's actually gonna turn into the ice cream.

So we're gonna mix our ingredients in here, and we're gonna start with our 1/2 cup of milk.

We're gonna pour that right in that bag there.

We're gonna take a tablespoon of just regular sugar, add that in there.

We're going to measure out a teaspoon of vanilla, and this is actually 1/2 a teaspoon.

So I'm gonna use two of these to make a whole teaspoon.

See those ingredients in there.

We're gonna zip it really tight.

And I'm gonna mix it up just a little bit here to make sure all our ingredients are all blended together.

And then you're gonna try to push out as much air as you can.

You want it to be really just those ingredients in there.

So not a lot of air.

Squeeze all that out as much as we can.

Make sure it's sealed really tight up at the top like that.

Now we're gonna take our bigger gallon-sized bag, and we're gonna put our two cups of ice (ice thuds) in there, and our 1/4 cup of table salt.

(salt swooshes) Pour that in there as well.

(bowl clinks) So, if you are to feel this bag, it is really, really cold.

So we talked earlier about adding heat to things makes them melt.

But when we're taking heat away, it's gonna turn it back into a solid or freeze it.

So when we're adding this ice and salt together, it's gonna pull all the heat out of there.

So instead of adding heat, we're taking it away.

So our hope is that we can turn this liquid here into solid ice cream.

So we're gonna use this as our cooler, and we're gonna put this right inside there.

Make sure it's sealed really tight again.

And seal this bigger bag as well.

So, instead of just letting it sit there, we're really gonna help that cold ice cool down that liquid and try to freeze it.

So, we're gonna shake it up.

It's gonna take a little bit of time.

(bag rattling) I'm gonna stop and take it out just to see where we're at.

I don't think we're quite done yet.

But if you take it out, you can see it definitely, it feels a lot colder, and it's starting to harden a little bit, but we're not quite there.

(bag rattling) Ooh!

It's really cold on my hands.

We don't like the ice cold.

(indistinct) Some gloves when we do this because it's really cold.

All right, let's check it one more time to see where we're at.

All right.

Still pretty liquidy.

It doesn't look ready quite yet.

All right.

That was tiring.

After a few minutes, maybe five minutes of shaking up our mixture here, I wanted to show you what we had so far because a few interesting things have happened.

So right now, if you look at this, it is not a liquid anymore.

It is a solid in there, but also I noticed that our solid ice has turned mostly to water.

So, we talked earlier about how, when things are turning from a liquid to a solid, that we're taking heat away.

So the heat that was inside that liquid that we've taken away, went here and turned our solid into a liquid, where it was pulling the heat out of this and turning it into a solid.

So, I'm gonna open this up for you and grab a spoon so that you can see our delicious ice cream.

You could do this with any different flavors you want.

It is edible.

It is delicious.

Mm, it's so good.

So this is a fun activity that you can do at home to really demonstrate how we can turn a solid into a liquid when we melt things like ice cream or Popsicles.

But you can also turn them back into a solid by taking heat away or cooling them down.

So, hopefully you can enjoy this activity at home with friends or family, and feel free to check out that recipe by Ruff Ruffman to help you along the way with the ingredients and the recipe.

Today, we learned so much about states of matter, solids, liquids, and gases, and that they can change between different states.

A solid can turn into a liquid, a liquid into a solid.

And we got to see what happens when we add or take away heat from a solid or a liquid.

So we got to experiment with solids like ice or our Popsicle.

So remember that solids have a definite shape.

So these ice cubes have a very specific shape.

And our liquids, like this cream or water, liquids take the shape of their container.

So they don't hold their own shape like a solid does.

We also got to experiment with heat and how heat changes or changes state of solids and liquids.

Like when we melted our Popsicle or watched our chocolate-covered pretzels melt on the heat pad.

I think my favorite part today though, was watching how this solid and this liquid could transfer heat.

So we took heat away from the cream and made it colder, and added heat to the ice cubes, which melted them.

And when that happened, our cream turned into a delicious ice cream snack.

I had so much fun sharing that with you guys today, and hopefully, you get a chance to observe and find some things in your home or around you that are solids and liquids and watch what happens when there's heat, either added or taken away.

Thanks so much for joining today.

I hope you had fun (light-hearted music) - [Announcer] "Teaching in Room 9" is made possible with support of Bank of America, Dana Brown Charitable Trust, Emerson, and viewers like you.