The Matter of Melting

Peggy Ashbrook

What’s happening at http://science.nsta.org/earlyyearsblog. What strategies do you use to challenge every child in class—those who can move faster and those who might need more time?

In keeping with this issue’s theme—Reaching the Hard to Reach—this month’s The Early Years column reveals how establishing a shared language through experiences can help young students and teachers exchange ideas and information about science concepts. Learning a language takes time, but should learning science wait until a language is learned? It’s not necessary to wait when a shared experience is the foundation for communication.

The experiences that occur as part of this month’s activity exploring changes in states of matter are common in many cultures and childhoods. Bringing these experiences into the classroom makes them part of the classroom culture and provides an opportunity to teach vocabulary and begin building your shared language.

Reading a story about one of these experiences will help students connect something from their own lives to the concept. “The warm wax is soft,” and “My hand melted the chocolate” are statements about shared experiences that, when grouped together, present the concept of states of matter. The language established by a shared experience is limited but useful—an important foundation from which to begin teaching science.

Your fellow early childhood educators are also discussing their ideas about how to reach “hard to reach” students, including students learning to speak English, online. Read some of their suggestions in the box at the bottom of the page, or visit http://science.nsta.org/earlyyearsblog to join the ongoing discussions yourself.

Melting and freezing activities familiarize primary students with the different states of matter and provide many opportunities for inquiry.

The Matter of Melting

The young child who asks, “Where is my ice cream?” when confronted by a bowl of milk an hour after leaving a bowl of ice cream will have a hard time grasping that a solid volcanic rock was once a red hot liquid. Unless they witness it, young children may not understand that solids can melt into liquids and liquids can become solids.

It is common for children to describe dissolving as melting. Perhaps the term “melting” is more familiar than “dissolving,” and children often use a word they know to mean a change took place. Doing melting and dissolving activities back-to-back would illustrate how the two processes are different.

And keeping a child’s attention while a solid melts completely can be a challenge. That is why when exploring melting, it’s worth it to repeat the experience a few times with various substances, including chocolate and wax.

Explore the topic of States of Matter

Learning about states of matter is often included in first-grade curriculums and is part of the National Science Education Standards Physical Science Content Standard B for grades K–4: properties of objects and materials.

The Standards state,

“Most students will have difficulty with the generalization that many substances can exist as either a liquid or a solid. K–4 students do not understand that water exists as a gas when it boils or evaporates; they are more likely to think that water disappears or goes into the sky. Despite that limitation, students can conduct simple investigations with heating and evaporation that develop inquiry skills and familiarize them with the phenomena” (NRC 1996).

Investigations into melting involve more than learning about changes in state due to changes in temperature—making predictions; using their senses (and tools such as a thermometer) to gather information; observing; describing and recording changes; and sharing explanations are science processes young students will gain practice in through this exploration.

Peggy Ashbrook is a preschool science teacher and author of Science Is Simple: Over 250 Activities for Preschoolers.

Reference

National Research Council (NRC). 1996. National science education standards. Washington, DC: National Academy Press.

Melt Away!

Objective:

• To learn that heating a solid can make a change in states called melting, which can be seen, felt, and measured.

Materials:

• Small beeswax balls (available at craft stores)
• Chocolate chips
• Thermometers

Check with parents to see if students have allergies to chocolate or dairy products before allowing them to handle the chocolate chips. There are brands of chocolate chips that are made without dairy products. Remind students that in a science laboratory no eating is allowed, but they will be able to eat the chocolate chips after the investigation.

Procedure:

1. To get students interested in the topic, talk about the states of matter—liquid, solid, and gas—throughout day. (Deep breath) Oh, it feels good to breathe in this air. I’m glad it’s a gas, not a liquid! Ouch! The block that dropped on my foot is a hard solid.
2. Give each child a small ball of wax and one chocolate chip to hold in each hand. Put a second chip and wax ball on a table in the children’s view.
3. Have the students describe the two substances, including which state of matter they fall into, and record their words. Ask students to predict what will happen to the chocolate chip and the beeswax ball in their closed hands and to the same items on the table. Record the students’ predictions.
4. Jump in place or march around the room so that at least some of the children’s hands will become warm enough to melt the chocolate chip. After 2–5 minutes, have all the children open their hands. Some chips will be more melted than others. Ask the students to describe what the chocolate chip and ball of wax feel like now.
5. Ask questions such as, “Did any change happen to the wax or chocolate?” and “Which is softer?” to begin a group discussion a bout any changes. This will lead to a discussion about melting. Have the children define the term melting and list other substances that they have seen change from a solid into a liquid, such as ice, ice cream, snow, or candles.
6. Using a thermometer, have students measure and compare the closed-hand temperature of children whose chips really melted and the closed hand temperature of children whose chips did not melt.

Extensions:

• Observe the change in state in the other direction (i.e., from liquid to solid) by making juice pops from frozen juice concentrate. Have the students feel the concentrate before thawing and then observe the solid after you make the pops.
• Freeze liquid paint in ice-cube trays, adding craft sticks for handles. Paint with the “melting” cubes.
• Melt a bar of glycerin soap in a clear glass bowl in a microwave oven. Have students watch the bar as it changes shape. Cool the liquid soap in an empty plastic margarine tub. Hot liquid soap should not be carried around the classroom.

Observing the melting of several different substances will strengthen students’ understanding that melting is a change in state from solid to liquid that can happen to many substances when heated, not a characteristic solely of the familiar ice. It’s fun to see that amazing change and important that young children get a range of experience with melting before learning in later grades about molecular structure differences between states of matter.

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