Unit Plan 5 (Grade 6 Science): Gravity & Orbits

Focus: Describe how gravity governs the motion of planets, moons, and other solar system objects, using models to show how gravitational attraction and forward motion together create orbits.

Grade Level: 6

Subject Area: Science (Earth & Space Science — Space Systems • Scientific Modeling)

Total Unit Duration: 5 sessions (one week), 50–60 minutes per session

I. Introduction

In this unit, students explore gravity as the invisible force that shapes the solar system. They investigate how gravity pulls objects with mass toward one another and how this pull, combined with an object’s forward motion, results in orbiting paths instead of straight-line motion. Through demonstrations, simulations, and diagrams, students model how gravity keeps planets in orbit around the Sun, moons in orbit around planets, and influences satellites, asteroids, and comets. They continue building MS-ESS1-2 skills in developing and using models to describe orbital motion.

Essential Questions

• What is gravity, and how does it act between objects in space like planets, moons, and the Sun?
• How does gravity, combined with an object’s motion, create orbits instead of straight paths?
• Why don’t planets and moons simply fly off into space or fall into the Sun?
• How can models help us understand the role of gravity in the structure and motion of the solar system, and what are the limitations of these models?

II. Objectives and Standards

Learning Objectives — Students will be able to:

1. Describe gravity as an attractive force between objects with mass, acting even across space.
2. Develop and use models (physical, diagram, or digital) to show how gravity pulls planets toward the Sun and moons toward their planets.
3. Explain that orbital motion results from a balance between an object’s forward motion and the pull of gravity, using everyday analogies (e.g., ball on a string, curved tracks).
4. Compare the role of gravity for planets, moons, and artificial satellites, identifying similarities and differences in their orbits.
5. Describe the strengths and limitations of their gravity and orbit models, connecting to MS-ESS1-2 expectations.

Standards Alignment — 6th Grade (NGSS-based custom)

• MS-ESS1-2 — Develop and use a model to describe the role of gravity in the motion of objects within galaxies and the solar system.
  • In this unit: students develop and use models to show how gravity keeps planets, moons, and satellites in orbit and influences their paths.

Success Criteria — Student Language

• I can explain that gravity pulls objects with mass toward each other, including in space.
• I can use a model to show how gravity pulls planets toward the Sun and keeps them in orbit.
• I can describe how an object’s forward motion plus gravity’s pull creates a curved path instead of a straight line.
• I can give examples of gravity’s role in the motion of moons and satellites.
• I can say what my gravity model does well and what it does not show accurately.