This high school STEM resource explores galaxy motion and the mystery of dark matter, helping students understand gravity, scientific investigation, and one of the biggest unanswered questions in physics. Best for: Physics, Astronomy, Space Science, STEM Includes: • 20 discussion and comprehension questions • Analytical essay prompt • Structured essay with paragraph guidance and sentence starters • Classroom debate activity • Critical thinking discussion questions Grades: 9–12, College, Adult Ed