Molecular Make-up, and How Thermal Energy Effects Changes in Three States of Matter

By Dexter Lane, Nature Explore Program Writer and Consultant

If I were a fifth-grader I’d be intimidated by the title of this project.  Then again, unlike Chapel Hill Academy, in Fort Worth Texas, my elementary school didn’t have a Nature Explore Classroom.  Rolando Sifuentes and Audrey Davidson, teachers at Chapel Hill, know how to make science come alive for their students.  In the midst of the fun they’re having outdoors, they learn complex scientific concepts such as the role of thermal energy in transforming ice into water, and water into water vapor. Let’s see how this works.

If I remember correctly, ice is a solid that when it finds itself in an environment above 32 degrees Fahrenheit, melts into water.  As a liquid, the water will assume the shape of whatever container holds it.  But when that water is heated to its boiling point, it vaporizes into steam, escaping the container, and dissipating into the surrounding atmosphere.  Thermal energy, delivered by the surrounding air, is the culprit in these transformations.  To really understand the three states of water, you have to understand this process on a molecular level.  For CHA students, probably unlike schoolchildren learning thermal energy transfer from videos and diagrams, this learning doesn’t feel like a lesson.  It is a complex science lesson.  But it’s also fun.

Before Chapel Hill’s children learn why and how thermal energy can transform matter, they must first transform themselves.  This process is charmingly simple. Each student becomes a molecule.  Some are ice molecules, and some represent thermal energy.

Students gather at a wooden platform in their Nature Explore Classroom, which they call the “OLC,” (Outdoor Learning Center.)  Children representing solid ice stand on the platform.  Other children, representing thermal energy, walk in a circle around their friends.

Rolando and Audrey direct the children’s movement into a representation of molecular behavior.  While children are imitating molecules, teachers question them about the science behind the exercise.

It goes something like this:

About twenty “ice molecule” children stand on the platform, with vibrating arms held up below their chins, as the remaining “thermal energy” students slowly circle them.

Teacher: “Where is the thermal energy found?”

Student: “On the outside.”

Teacher: “Where?”

Student walking around the platform: “Here!”

Teacher: “Now faster—thermal molecules! … So now what’s happening to that solid? You’re going to need to get a little more room, so start expanding a little bit.”

As the children representing thermal energy increase speed, children on the platform vibrate their arms more quickly, and begin to move around, bumping into each other—but staying on the platform.

 The students pause in the action to discuss the process they’re enacting.

Teacher: “What’s happening, Brandon?”

Brandon (student): “They can’t go everywhere, so they stay here!”

Teacher: “Yes—stay within that area, but move further apart.  You’re not so close together any more.  You were solid ice and now you’re a liquid.”

Children on the platform move further apart.

Teacher: “What’s the next state?  What do we have to do to change this liquid state of matter into steam?  Am I just going to say ‘Hey Mia, evaporate?’ Is this going to work?”

Student:  “Add thermal energy.”

The action resumes, as children take up the full surface of the platform, and move more rapidly. Bumping into each other, they laugh excitedly.

Teacher: “We need more thermal energy.”

The thermal energy children begin to run around the platform.

Teacher: “You’re now gas molecules, and gas can move throughout.”

With that, giggling students leave the platform and all children move randomly throughout the outdoor classroom.

Teacher: “Jocelyn—you’re a gas molecule.  Peter, I see you, you’re a gas molecule.”

Of course the molecular thermodynamics of ice becoming water becoming water vapor can be taught using videos and diagrams.  Elementary school students can be expected to learn this concept, but how invested are the majority of them in this lesson?  Sadly, studies show that children in the US start losing their natural interest in science by the fourth and fifth grades.  For many, learning the states of water on the molecular level is just another lesson, to which they have to pay attention, because they’ll be tested on it.

But for the fortunate children at Chapel Hill Academy, this learning is joyous.  It’s a lesson learned outside, playfully, with friends.  It’s a lesson learned kinetically and intellectually.  It’s a lesson in which teachers aren’t just delivering information to their students, but also having fun with them in the process.  It’s a lesson that bonds teacher and student, inspiring both.

What will happen during test time?  I imagine the children who have learned indoors via video, diagram, and instruction will be anxiously trying to assemble what they were taught into the right answer.  Maybe I’m wrong, but I’ll bet that a higher percentage of Rolando and Audrey’s students will answer the questions correctly.  And some of those children will look up, enter briefly into a memory, and smile.