Heat Shifters Slides
Grade 4 Physical Science
Energy in Action
Heat Shifters
Discover how thermal energy moves, expands matter, and transforms our everyday world.
Particle Energy
Expand & Shrink
State Changes
Science Mystery Case File #1
The Bridge That Couldn't Close
On a scorching 100°F summer day, a steel drawbridge opened for a ship. But when operators tried to close it, the two steel halves jammed tightly together!
Cool Morning
The steel was at normal size. There was plenty of room for both sides of the bridge to open and shut smoothly.
Blazing Afternoon
After baking in intense heat, the bridge grew longer! Firefighters had to hose it down with cold river water to shut it.
Investigation Question: How can heat make solid steel grow bigger?
Core Concept Thermal Energy
Heat is Energy in Motion
Everything around you is made of tiny particles. Thermal energy is how fast those particles jiggle!
Cold Particles
Move slowly and stay huddled close together. They vibrate in place with low energy.
Slower Motion • Packed Closer
Hot Particles
Zip around rapidly and bounce off each other. They push outward and need more room!
Faster Motion • Spread Out
Golden Heat Rule: Heat ALWAYS flows from warmer objects to cooler objects!
Effect 1 Changing Size
Expansion & Contraction
When temperature changes, objects physically grow or shrink.
Thermal Expansion
When matter absorbs heat, particles move faster and bounce farther apart. The object expands (grows larger).
Example: Liquid expands up a thermometer tube as it warms up!
Thermal Contraction
When matter loses heat, particles slow down and pull closer together. The object contracts (shrinks smaller).
Example: A party balloon shrinks when taken outside in the cold!
Key Idea: The number of particles stays the same—only the space between them changes!
Mystery Solved Engineering Solutions
Designing for Heat Expansion
Engineers must leave room for materials to stretch and shrink safely!
Expansion Joints
Metal comb-like teeth on bridges slide into each other as the bridge expands on hot days.
No Cracking!
Railroad Gaps
Tiny gaps between train rails give steel tracks room to stretch without bending like spaghetti.
Smooth Rides
Sidewalk Cracks
Grooves cut into concrete slabs let sidewalks expand without buckling or smashing into pieces.
Safe Walkways
Without expansion gaps, summer heat would bend bridges and buckle highways!
Effect 2 State Changes
Heat Changes States of Matter
Adding or removing thermal energy can transform a solid, liquid, or gas!
Solid (Ice)
Particles locked tightly in place.
+ Add Heat → Melts
Liquid (Water)
Particles slide smoothly past each other.
+ Add Heat → Evaporates
Gas (Steam)
Particles fly fast and spread far apart.
− Cool Down → Condenses
Heating: Solid → Liquid → Gas | Cooling: Gas → Liquid → Solid
Effect 3 Heat Flow
Conductors vs. Insulators
Different materials handle the flow of heat energy in very different ways!
Thermal Conductors
Materials that let heat pass through them quickly and easily.
Common Examples:
Metals (iron, copper, aluminum), steel pots, gold
Thermal Insulators
Materials that slow down or block the movement of heat energy.
Common Examples:
Wood, rubber, plastic, styrofoam, wool jackets
Why does a metal spoon in hot soup burn your tongue, while a wooden spoon stays safe to touch?
Class Challenge
Detective Time
Heat Detective Showdown
Use what you learned today to solve these two everyday science puzzles!
1
The Stuck Jar Lid
A pickle jar lid is screwed on way too tight. Your teacher runs hot tap water over just the metal lid for 20 seconds. It pops right off! Why did that work?
Hint: Think about which material expanded first!
2
The Sagging Power Lines
In deep winter, overhead electrical cables hang tight and straight between poles. In July, they droop down low toward the street. Why?
Hint: Think about what metal wires do when heated!
Key Takeaway Heat makes particles dance faster, spread apart, and change the world around us!
