Week 14 Hands-On Science script of Abecedarians, by Robyn Cooper Today we are learning about heat transfer called conduction. And then we are learning about surface tension. [Use the printable images at the end, if you like].

Before we start science today, let’s sing the scientific method. [Sing the song.]

Experiment 165. Cold Feet.We are going to talk about heat transfer first. Our experiment is called “cold feet”. What’s our Question? How does the transfer of heat work?

To research, we ask ourselves “What do you know about heat?”

When is heat produced? Heat is produced when something vibrates. Everybody, shake your body. That’s what atoms and molecules look like when they are vibrating.

Energy causes atoms and molecules to always be in motion. They either bump into each other or vibrate back and forth to cause energy, which makes friction, which makes heat.

Put your hands together. They feel pretty normal. Now, rub your hands together very fast. What did you notice? They feel warmer?

What else is produced by something vibrating? SOUND! We learned last week that when water or air vibrate very very quickly together in the pattern of a wave, that makes sound. But when atoms and molecules vibrate randomly, it makes heat. This is called conduction.

There are certain types of atoms called metals.

Here is a periodic table (show a periodic table, below). Scientists have grouped certain atoms together because they like similar things and they act in similar ways. It’s kind of like how you could say all animals belong in a group. But dogs bark and eat meat. And all birds have wings. Or all fish need water. Or my family likes to hike, eat fish, and go to sleep at 8 o’clock. Your family may like to swim, eat pizza and go to sleep at 9 o’clock. The members of the oxygen family all act a certain way, the members of the nitrogen family all act a certain way, the member of the noble gas family all act a certain way, but also members of the metal family all act a certain way.

Let’s describe the Metal Family. Think of it like this. If someone keeps bumping into you, but you don’t want them to do that, how do you feel? Maybe you’re sad or angry.

If you were to bump into a molecule, it’s like you make it angry. And if it’s angry, it’s electrons start shaking. Everyone hold an imaginary ball, but pretend it’s shaking really fast.

It’s uncomfortable for the Metal, so it wants to give that crazy electron ball away.

Well, let’s pretend your name is Aluminum and you’re part of the Metal Family. Well, people in the Metal family get angry easily. You don’t have to bumped a lot to get angry. You get angry because all your electrons are vibrating so much, they are difficult for you to hold.

And when Mr. Foot steps on you, it makes your electrons vibrate. Aaaand, you’re pretty jealous. Mr. Foot is warmer than you, and you want some of his heat.

But here’s the good news. The heat wants to come to you and leave Mr. Foot until you, Aluminum Metal, and Mr. Foot are both the same temperature. And your brothers and sisters want to help you out, so they’ll take that crazy vibrating electron quickly from your hands to try to calm you down. And that keeps happening. And the more you bump into the members of the Metal Family, the crazier the vibrations are, and the more quickly your sisters and brothers will pass those crazy electrons around.

Have you ever gone bowling? You zoom the heavy ball down the lane. Well, the passing of the electrons is so fast in the Metal Family, it’s like zooming big bowling balls down a metal bowling lane. It’s really, really fast. And all that passing around, lets you take some heat away from Mr. Foot. The trick is, you all had to work together to get some of that heat. And more heat that is transferring, the faster that ball is being taken down the lane.

Well, now let’s pretend you’re part of the Carpet Family. Your name is Wool Carpet. The Carpet Family is very fancy, and so I’m going to use big words to describe them. Carpet is made of fabric which are usually plant fibers, which are made of Carbon, Hydrogen and Oxygen which live in a chain of polymerized sugar molecules called cellulose. Fancy, right?

Mr. Foot steps on you and makes your electrons vibrate. You’re also pretty jealous. Mr. Foot is warmer than you, and you want some of that heat. Here’s the good news. The heat wants to come to you and leave Mr. Foot until you the same temperature.

But now you have a problem, since you’re part of the Carpet Family. Because the members of your Carpet family are also pretty stubborn. So when Mr. Foot steps on you, your electron ball starts vibrating, but your sister or brother DOES NOT want to take it from you. It’s like your sister sees you struggling with a crazy electron ball but says, “oh well, I guess you have to deal with it.” These are poor conductors of heat. But that means you can’t take as much heat from Mr. Foot! You’re pretty sad.

So if you look at a bowling lane made of fabric, instead of metal, you’d have to watch a long time for that crazy electron ball to move down the lane. The ball WOULD move, but much slower. Well, the slower your sisters take the crazy electron ball away from you, the less heat is transferred. That just how the Carpet Family is.

Temperature always flows from the hottest to coldest source. Your foot is warmer than the air. Your body is about 98 degrees Fahrenheit. The room is about 30 degrees cooler. When you put your foot on the aluminum or carpet, the heat from your foot wants to go into the aluminum or carpet because they are colder.

So let’s do our experiment.

What do you see here?Foil and carpet.

Aluminum is a metal. Carpet is a fabric. You’re going to put your foot on each one, and notice the temperature.

Are they solid, liquid or gas?Solid.

Can the atoms and molecules in the carpet and aluminum vibrate?Yes.

Do they have a temperature?Yes.

Where does the temperature come from?The air in the room.

We are going to put our feet on these and feel their temperature.

Let’s make a hypothesis. Which one do you think will feel hotter: aluminum or carpet? Why?

Now let’s do our experiment. Put one foot on carpet, and the other foot on aluminum metal.

Let’s analyze our results. Which one felt hotter, aluminum or carpet?

What’s our conclusion? The carpet felt warmer because it’s not able to steal the heat from your foot. The aluminum felt colder because it’s stealing heat away from your foot.

Why?Aluminum metal is a better conductor of heat. Its metal molecules took electrons from each other a lot faster than the fibers’ molecules.

Experiment 171. Pepper Run. Now we are going to learn about the surface tension of water.

Everybody hold hands and just push gently on each others hands. Water does this same thing. Water molecules hold hands. They don’t want to let go of each other, and they like to press onto each other just slightly.

Have you ever seen a water bug or a water strider sitting on the water? How can they do that?The bug is less dense than the water, and is not putting enough pressure on the surface of the water to break the water tension. [see image]

What do you think will happen if I sprinkle pepper flakes on this water?They float.

The first question to ask is why the pepper flakes float. Why don’t they sink or dissolve in the water? Well, pepper is hydrophobic, meaning that water is not attracted to it. Because of that, the pepper can't dissolve in the water. But why do the flakes float on top of the water? Water molecules like to stick together. They line up in a certain way that gives the top of the water surface tension. Because pepper flakes are so light, and hydrophobic, the surface tension keeps them floating on top.

What do you think will happen to the pepper if I touch the water with a little bit of soap?Take guesses.

Let’s do it. What happened?The pepper shoots to the sides of my dish.

Why did that happen?Soap is able to break down the surface tension of water—that’s part of what makes soap a good cleaner. As the soap moves into the water, and the surface tension changes.

But the water molecules still want to keep the surface tension going, so they pull back away from the soap, and carry the pepper along with them.

See this at home: https://youtu.be/ho0o7H6dXSU

Do you think soap is the only substance that can break down water's surface tension? Try conducting the same experiment but with olive oil or hair spray. Do you think the pepper flakes will react in the same way?