MS-PS2-4: Arguing That Gravity Attracts and Depends on Mass
Also called NGSS MS-PS2-4 · Topic: Forces and Interactions · Physical Science
The Official Wording
Construct and present arguments using evidence to support the claim that gravitational interactions are attractive and depend on the masses of interacting objects.
Clarification statement: Examples of evidence for arguments could include data generated from simulations or digital tools; and charts displaying mass, strength of interaction, distance from the Sun, and orbital periods of objects within the solar system.
Assessment boundary: Assessment does not include Newton’s Law of Gravitation or Kepler’s Laws.
NGSS Lead States, 2013 · Read it on nextgenscience.org · checked October 15, 2026
What MS-PS2-4 Means in Plain English
Middle schoolers build an argument from evidence that gravity always pulls objects toward each other and that the pull is stronger when the objects have more mass. Evidence can come from simulations, data tables or the motions of the sun, moons and planets.
Students describe the pattern in words, without the formula for universal gravitation or Kepler's laws of orbits. This builds on 5-PS2-1, where Earth's gravity pulls objects down, and leads to MS-ESS1-2, where gravity explains the motions in the solar system.
MS-PS2-4 I Can Statements
- I can argue from evidence that gravity always attracts.
- I can explain how more mass makes gravity stronger.
- I can use data from a simulation to support a claim.
MS-PS2-4 Worked Example
An argument built from a gravity simulator, where students set two masses and read the pull between them.
Does gravity pull two objects together, and does the pull grow when one of them has more mass?
Set It Up: A gravity simulator with two balls, mass sliders, force arrows and a force readout, plus a claim, evidence and reasoning chart.
- Set both balls to 50 kg, 1 m apart, and read the force on each.0.000000167 N, arrows pointing at each other
- Raise one ball to 100 kg and keep the distance the same.0.000000334 N, the pull doubled
- Set both balls to 100 kg.0.000000667 N, four times the start
- Try many settings, looking for any arrow that points away.Arrows always point toward the other ball
- Compare with Earth pulling on a 50 kg student.About 490 N, billions of times more
The pull between the balls was always attractive and grew in step with the mass, and Earth's huge mass explains why its pull is the only one we feel.
Why it works: Every object with mass attracts every other, and the force depends on the masses, so everyday objects tug on each other very weakly while a planet pulls hard.
Common Mistakes with MS-PS2-4
Thinking gravity needs air or contact
“There is no gravity in space because there is no air.”
Try this: Gravity acts across empty space. The sun holds the planets in orbit from millions of kilometers away, with no air in between.
Thinking only big objects have gravity
“My pencil has no gravity.”
Try this: Every object with mass pulls on every other. A pencil's pull is real but far too weak to notice, because its mass is tiny.
Making a claim with no evidence
“Gravity depends on mass because it just does.”
Try this: Back the claim with data, like the simulator force doubling when one mass doubles, and explain why that data supports it.
Where MS-PS2-4 Fits
Practice MS-PS2-4
Quick Check
- A dropped apple falls to Earth. Why don't we see Earth move up toward the apple?
- Which pulls harder on a spacecraft at the same distance: the Moon or Jupiter?
- Is gravity ever a push?