How Temperature Changes Affect Metal in Iowa Factories
Thermal expansion is a real concern in Iowa industries such as manufacturing, agriculture, and infrastructure—especially during seasonal temperature swings.
A metal plate with two seemingly identical holes is tested using a metal pin. The pin fits easily into one hole but not the other. After the plate is heated, the same pin now fits into the previously too-small hole. When the plate is rapidly cooled with the pin still inside, the pin becomes firmly stuck. This surprising sequence of events connects to how heat affects materials, and how tools, machinery, building materials, roads and train tracks behave in Iowa’s climate.
Iowa Core Standard
Develop and use models to illustrate that energy at the macroscopic scale can be accounted for as a combination of energy associated with the motions of particles (objects) and energy associated with the relative position of particles (objects)
Driving Question
- How does heating and cooling a material change its shape or size enough to affect how parts fit together?
Probing Questions
- What did you expect to happen when the metal was heated? What actually happened?
- What might be happening to the particles inside the metal as it heats and cools?
- How might this affect real-world tools, machines, buildings, train tracks or bridges?
Classroom Suggestions
Students could:
- Draw or model molecular spacing in solids, liquids, and gases before/after heating.
- Conduct or observe a metal ball and ring apparatus demonstration. A metal ball won’t fit through a ring at room temperature, but will when the ring is heated.
- Explore design challenges where thermal expansion must be accounted for (e.g., bridge joints, pistons, tools).
- Conduct or observe a bimetallic strip bending demonstration. A strip made of two metals bonded together bends when heated due to differing expansion rates. This phenomenon is applied in home thermostats.
Resources
- PhET Simulation | States of Matter: This interactive simulation helps students visualize particle motion and temperature changes in solids, liquids, and gases.
- Science Buddies | Curl Metals with Heat: This site gives step-by-step instructions to test the ideas of bimetallic strip bending using household supplies. Video included.
- Teacher-Created Resource | Heat Makes Metal Change- But How?: Student handout with instructions for completing a simple test to investigate thermal expansion using household supplies. Includes a key.
- Accuweather | Car Goes Airborne After Heat Buckles Road: Captured in the Midwest, this video shows how extreme heat can expand the concrete of a road and cause a sudden and exciting change.
- Just Be Handy | How to Open a Tough Jar: Video demonstrating how these concepts can be used by heating the lid to more easily open a tough jar.
Contributors
Contributed by Kim Poeckes as part of the Iowa STEM Teacher Externship program.
Funding for Iowa Science Phenomena Provided By
