Unit Plan 19 (Grade 8 Science): Kinetic Energy & Speed
Grade 8 NGSS unit where students graph kinetic energy changes with mass and speed, using data to explain why small speed increases greatly boost energy of motion.
Focus: Graph and analyze relationships between kinetic energy, mass, and speed, using data from investigations and simulations to describe how energy of motion changes.
Grade Level: 8
Subject Area: Science (Physical Science • Energy • Data & Graphing)
Total Unit Duration: 5 sessions (one week), 50–60 minutes per session
I. Introduction
Students zoom in on the energy of motion—kinetic energy—and explore how it depends on an object’s mass and speed. Through hands-on trials and/or simulations, they compare carts or balls that are heavier vs. lighter and faster vs. slower. They then construct and interpret graphs (kinetic energy vs. mass, kinetic energy vs. speed) to look for patterns. By the end of the week, students can describe why small changes in speed can have big effects on kinetic energy and how this connects to safety, sports, and everyday motion.
Essential Questions
- What is kinetic energy, and how is it different from just “moving fast”?
- How does changing an object’s mass affect its kinetic energy?
- How does changing an object’s speed affect its kinetic energy, and why does speed matter so much?
- How can graphs help us see and describe the relationship between kinetic energy and mass or speed?
- Why does understanding kinetic energy matter for real-world decisions about safety, design, and sports performance?
II. Objectives and Standards
Learning Objectives — Students will be able to:
- Define kinetic energy qualitatively as the energy of motion that depends on both mass and speed.
- Collect or interpret data sets where mass varies and speed is held roughly constant, and construct a graph of kinetic energy vs. mass.
- Collect or interpret data sets where speed varies and mass is held constant, and construct a graph of kinetic energy vs. speed.
- Describe patterns in those graphs (e.g., kinetic energy increases with mass; kinetic energy increases dramatically with speed) in clear, everyday language.
- Use graphs and data to compare scenarios (e.g., heavier vs. lighter, slower vs. faster) and argue which has more kinetic energy.
- Explain, using graphs as evidence, why small increases in speed can lead to much greater kinetic energy and why this matters in real contexts (e.g., car safety, sports).
Standards Alignment — 8th Grade (NGSS-based custom)
- MS-PS3-1 — Construct and interpret graphical displays of data to describe the relationships between kinetic energy and mass or speed.
- In this unit, students make and interpret graphs of kinetic energy vs. mass and kinetic energy vs. speed from investigations or simulations.
Success Criteria — Student Language
- I can explain that kinetic energy is the energy of motion, and it depends on both mass and speed.
- I can construct graphs that show how kinetic energy changes when mass changes and when speed changes.
- I can interpret those graphs to say which situations have more or less kinetic energy and why.
- I can describe the pattern in the graphs: what happens to kinetic energy as mass increases, and what happens as speed increases.
- I can use graph evidence to explain why going a little faster can make impacts and collisions much more dangerous.