Thermal Motion Teacher Guide Teacher Guide: Particle Power
Unit: Thermal Energy & Phase Changes
TOTAL TIME: 40 MIN
GRADES: 6-7
Learning Objective
Students will analyze how thermal energy relates to particle motion and phase changes through visual evidence and simulation data.
1. The Hook (5 Minutes)
Show the class a picture or short clip of a boiling beaker. Ask the key question:
"The video showed water turning to steam. What was underneath the beaker?" (Answer: Fire/Heat)
Prompt for discussion:
Why does heat make particles move faster?
Does adding heat change what the substance is, or just how it behaves?
2. Video Analysis (10 Minutes)
Video: "Particle Motion in Matter" (YouTube URL provided in lesson plan)
[0:38] Pause Point:
Ask: "If the particles are stuck in place, can an ice cube change its shape on its own?" (No, they only vibrate in a fixed lattice).
[0:58] Pause Point:
Ask: "How is this different from the solid? Why does water splash when you jump in it, but ice doesn't?" (Particles slide past each other).
[1:21] Pause Point:
Ask: "Which state has the most empty space? Which is easiest to compress?" (Gas has the most space and is easiest to squish).
3. Simulation & Mapping (20 Minutes)
Direct students to the PhET "States of Matter" simulation. Focus on the "Phase Changes" tab.
Key Observation
If we cool the gas down, what happens to the speed? What is this called? (Condensation)
Flow Chart Task
Students must complete the "State Shift Worksheet" tracing energy from Ice to Steam.
4. Extension (5 Minutes)
Discuss thermal expansion in the real world:
Bridges in Summer: Why do they have gaps? (Expansion joints prevent buckling).Tires in Winter: Why do they look flat? (Gas particles move slower and take up less space).
Material Prep
Projector
Loaded with the "Particle Power Slides"
PhET Simulation
States of Matter: Basics
Worksheets
1 per student: State Shift Template
Whiteboard
For drawing shared class diagrams
Common Pitfalls
Watch out for the misconception that "particles in solids don't move." Remind students they are always vibrating unless they are at absolute zero!
Key Vocabulary
Vibrate Solids
Flow/Slide Liquids
Random Gases
Expansion Adding Heat
Particle Power Slides Particle Power
Thermal Energy & State Changes
Phase Investigation 01
Wait... what's happening?
In a laboratory, a scientist boils a beaker of water. Steam begins to fill the room.
"What was underneath the beaker?"
Hint: It rhymes with "Treat"!
Field Evidence
Video: Particle Motion
Embedded media
1
Watch Particles
2
Spot the Pattern
3
Pause for Discussion
State: Solid
The Vibe
Particles are tightly packed in a fixed, orderly grid.
Movement
They vibrate in place but do not move freely.
State: Liquid
The Vibe
Particles are close together but not in a fixed arrangement.
Movement
They move and slide past each other, like marbles.
State: Gas
The Vibe
Particles are far apart with lots of empty space.
Movement
They move freely at high speeds in all directions.
Digital Investigation
Open the PhET "States of Matter" Simulation
Step 1: Cool Down
Cool the gas until it becomes a liquid. What happens to the speed?
Step 2: Map It
Complete the flow chart on your worksheet as we go.
Step 3: Analyze
Does more energy mean more or less "freedom" of movement?
Real World Expansion
Summer Bridges
Why do bridges have metal "teeth" gaps?
The particles are getting more energy and need space to spread out!
Winter Tires
Why do your car tires look flat when it gets freezing outside?
The gas particles slow down and take up less volume!
State Shift Worksheet State Shift Lab Report
Thermal Energy & Particle Motion
Name:
Date:
1 Thermal Energy Observation
Think back to the video. When heat (energy) was added to the ice, how did the movement of the blue particles change?
2 Phase Shift Flow Chart
Trace the path of water as it gains energy. Use the word bank below to label each stage and describe the motion.
ICE
Add Heat
Describe Motion
WATER
Add Heat
Describe Motion
STEAM
Word Bank
Faster Vibration Rapid Random Motion Fixed Arrangement Sliding / Flowing
3 Investigation: Cooling Down
During the PhET simulation, what happened to the particle speed when we removed thermal energy from the steam? What state of matter did it become?
Critical Thinking: Thermal Expansion
Why do bridge builders leave "expansion joints" (gaps) in the concrete roads? Use the word Particles in your answer.
State Shift Answer Key Answer Key
State Shift Lab Report
Teacher Reference Guide
1 Thermal Energy Observation
When heat was added, the particles began to vibrate faster. Eventually, they broke free from their fixed grid and started to slide past one another.
2 Phase Shift Flow Chart
ICE
Add Heat
Faster Vibration
WATER
Add Heat
Rapid Random Motion
STEAM
3 Investigation: Cooling Down
Answer:
The particle speed slowed down. The state became a liquid (Condensation). If cooled further, it would become a solid again (Freezing).
Thermal Expansion Key Points:
Bridges need gaps because as the sun heats the concrete, the particles move faster and spread out, causing the bridge to expand. Without gaps, the bridge would buckle or crack.
