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8th Grade Physical Science Lesson

Drop, Roll, and Transform: Energy on the Move

Shared by A STEM Educator

8th GradeNGSS Phenomenon-BasedMS-PS3-2, MS-PS3-545 min
Learning Objective

Students will develop and use models to explain how energy is conserved and transformed between gravitational potential energy and kinetic energy in mechanical systems, addressing MS-PS3-2 and MS-PS3-5.

Lesson Overview

Students investigate how gravitational potential energy converts to kinetic energy (and vice versa) using marble-and-ramp experiments, skate park diagrams, and roller coaster engineering challenges. The anchor phenomenon — a roller coaster car that completes a loop without falling — drives inquiry into why height determines speed.

Materials

  • Foam pipe-insulation tubing (cut in half lengthwise) — 1 per group, ~1.5 m long
  • Marbles (at least 3 per group)
  • Metric rulers and meter sticks
  • Books or blocks for propping ramps at different heights (3 height levels)
  • Stopwatches or phones with timer apps
  • Tape for marking a finish line on the floor
  • Graph paper or printed coordinate grid sheets
  • Printed skate park track diagrams (one per student)
  • Calculators
  • Printed investigation handout (one per student)
  • Sticky notes (2 colors per group)

Scaffolded Task Progression

1Task 1
Warm-Up — Marble Ramp Speed Measurement

Set up your foam ramp at three different heights: low ( cm), medium ( cm), and high ( cm). Release a marble from the top of the ramp and measure how far it travels horizontally across the floor after leaving the ramp's end (mark the landing spot with tape). Record your results in the table below.
Ramp Height (cm)Horizontal Distance Traveled (cm)
5
10
20

Describe the pattern you see. What does a greater horizontal distance tell you about the marble's speed at the bottom of the ramp?
2Task 2
**Skate Park Energy Mapping** Study the skate park track profile below. Label each marked point (A–E) with either **MAX GPE**, **MAX KE**, **Min GPE**, **Min KE**, or **Equal GPE and KE** (some labels may be used more than once). ```coordgraph {"title":"Skate Park Track Profile","xLabel":"Position","yLabel":"Height (m)","xRange":[0,10],"yRange":[0,6],"xStep":1,"yStep":1,"polylines":[{"points":[[0,5],[2,5],[3,0],[5,3],[7,0],[9,4],[10,4]],"color":"#1d4ed8"}],"points":[{"x":0,"y":5,"label":"A"},{"x":3,"y":0,"label":"B"},{"x":5,"y":3,"label":"C"},{"x":7,"y":0,"label":"D"},{"x":9,"y":4,"label":"E"}]} ``` Then answer: At which point does the skater move fastest? At which point could the skater coast the farthest if the track suddenly ended?

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