Dark Matter and Universal Gravitation

Students use Newton's Law of Universal Gravitation to analyze the motion of stars in a galaxy. An interactive "Predict, Observe, Explain" teacher demonstration prompts students to connect the orbital speed of stars with the mass interior to the orbit. In the activity worksheet, students plot the measured speed of stars versus their orbital radius, and then calculate the expected speed of the stars based on the luminous mass of the galaxy.


  • Lesson plans: Dark Matter and Universal Gravitation
  • Videos: The Mystery of Dark Matter (approx. 30 min)
  • Activities: Dark Matter Within a Galaxy (worksheet and solutions)
  • Demonstrations: Uniform Circular Motion
  • Supplementary Materials: Dark Matter in a Nutshell and more
  • Teacher-provided Materials: Centripetal motion apparatus (string, rubber stopper, washers, plastic tube, paper clip)

(Note: all lesson plans and worksheets provided as PDFs and modifiable MS Word documents)

Intended Audience: Senior High (Gr 11-12)
Lesson Topics: Astronomy, Circular Motion, Gravity
Price: Free