Unit Overview

Students discover gravity is constant invisible force affecting all objects with mass pulling them downward. Through solving optical illusion mysteries with bowling balls or investigating falling object experiments, conducting four lab stations dropping ping pong balls, building pendulums, and testing air resistance proving gravity pulls consistently, and engineering parachute delivery systems using air resistance slowing gravity's pull, students master gravitational concepts.

  • Lesson 1
    Lesson 1: Solve: Uphill Mystery + Vocabulary Mind Map

    Solve: Uphill Mystery + Vocabulary Mind Map

    Billy and Dullis share summer vacation videos—Billy's first skydive, Dullis's embarrassing tree fall—both caused by gravity. Then Mosa's video shows something impossible: her bowling ball rolling uphill! Students investigate the mystery, examining the footage closely and testing similar scenarios. The revelation: it's a visual illusion! The background creates the perception of uphill when the ball is actually rolling downhill. Every object follows gravity's predictable pull toward Earth's center—no exceptions. What looks like defying gravity is just tricky perspective.

  • Lesson 2
    Lesson 2: Make: Lab Stations: Experience Gravity

    Make: Lab Stations: Experience Gravity

    Four gravity investigation stations with ping pong balls, meter sticks, and paper. Station 1: Drop ping pong ball from different heights—measure how far it falls, observe it always falls downward. Station 2: Create pendulums with string and balls, release from different positions—mark targets showing gravity's consistent pull. Station 3: Drop flat paper vs. crumpled paper—same mass, different air resistance, different fall times (but same downward direction). Station 4: Build ramps with chopsticks—balls always roll down, never up. Students draw arrows representing gravity's pull, comparing initial vs. final object positions, proving gravity consistently pulls objects toward Earth.

  • Lesson 3
    Lesson 3: Engineer: Apply your Knowledge to Engineer a Safe Food Drop

    Engineer: Apply your Knowledge to Engineer a Safe Food Drop

    Design a delivery system that safely drops supplies to disaster relief areas using knowledge of gravity and air resistance. Students research parachute designs, calculate how air resistance opposes gravity's pull (slowing descent), then engineer prototypes using paper, string, bubble wrap, tissue paper, cardboard, cloth, and cotton balls. They test by dropping packages from heights, measuring fall times and impact damage. Successful designs balance gravity's downward force with air resistance's upward push—delivering supplies gently instead of smashing them. Real-world physics meets humanitarian engineering.

  • Next Generation Science Standards
    5-PS2-1
    Support an argument that the gravitational force exerted by Earth on objects is directed down. [Clarification Statement: “Down” is a local description of the direction that points toward the center of the spherical Earth.] [Assessment Boundary: Assessment does not include mathematical representation of gravitational force.]
  • Inquiry Scale
    • Each lesson in the unit has an Inquiry Scale that provides directions on how to implement the lesson at the level that works best for you and your students.
    • “Level 1” is the most teacher-driven, and recommended for students in 4th-5th grades. “Level 4” is the most student-driven, and recommended for students in 7th-8th grades.
    • For differentiation within the same grade or class, use different inquiry levels for different groups of students who may require additional support or an extra challenge.
  • Common Misconceptions
    • Students initially think that air or some other force “pushes” them down towards earth. Emphasize that gravity is an attractive force that pulls objects towards earth rather than a force that pushes them.
    • Students often think that gravity only applies when they are falling or when they are in the air. Emphasize to students that gravity is acting on them even when they are standing, sitting, or lying down!
    • Students sometimes think that they are defying gravity when they jump up in the air. Use the vocabulary word, “force,” to discuss how jumping is an opposing force to gravity.
  • Vocabulary
      • Force
      • Gravity
      • Acceleration
      • Air Resistance
      • Earth
  • Content Expert
    • Glennys Farrar, Ph.D.
      Professor of Physics Theoretical Particle Physics, Astrophysics and Cosmology New York University
  • Leveled Reading

    * To give our users the most comprehensive science resource, Mosa Mack is piloting a partnership with RocketLit, a provider of leveled science articles.

    • Why are Planets Round?

      This article explains how gravity works to pull planets and stars together into spheres.

    • Space Tug o' War!

      Why doesn't the Earth fall into the Sun? In this article, we define the terms mass, gravity, orbit, and velocity. This article serves to introduce students to the ideas behind why planets are able to stay in orbit by flying through space at just the right velocity, and with just the right amount of gravitational pull from their star.

    • They All Fall Down

      In this article, students read about the different ways that gravity changes the landscape through creep, mass wasting, landslides, or rockfall.

    • Potential Energy and Distance

      In this article, we look at the way that potential energy is stored in objects that are farther away from the ground. Using the example of a of roller coaster, we define the word "system" and talk about the benefits of using a model to look at the relationship between potential energy and distance

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