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Does Mass Matter?

Physical Science — Forces & Motion | Unit 1, Lesson 5 of 6

📚 Grade: 5th Grade⏱️ Duration: 45–60 minutes🔬 Subject: Physical Science — Forces & Motion
⚖️🪙
Mass can affect how easily motion changes.
📋 NGSS Standard:
5-PS2-1 — Support an argument that the gravitational force exerted by Earth on objects is directed down.

🎯 Learning Objective

Students will test how adding mass can change an object’s motion in a force investigation.

💡 The Big Idea

Objects with more mass can respond differently to the same push, so scientists compare tests carefully and look for evidence patterns.

🔬 The Science

Science Snapshot
Smaller masseasier to speed upbigger motion changeless resistance to pushLarger massharder to change motioncan push farther in collisionneeds more force for same changecompare
The same force can produce different motion changes when mass is different.

What is happening?

Mass matters in force interactions because heavier objects are harder to speed up, slow down, or redirect than lighter ones when the same force is applied. Mass also affects what happens when objects collide.

Why it works that way

A larger mass can keep moving through a collision more strongly, while a smaller mass may show a bigger motion change. This does not mean heavier always means faster; it means the response to the same push or impact can be different.

Look for this in the lesson

Students should compare cases with similar pushes but different masses. The goal is to notice how much the motion changes, not just which object “wins.”

Ask while you read: If two objects get the same push, how might their masses change the outcome?

📦 Materials

🏠 Household Items to Gather

📋 Printables

🧪 Investigation

Step 1 — Make a light and heavy version (5–10 min)
Use the same object and add coins or washers to one version.
Step 2 — Run the same test twice (10 min)
Use the same ramp height or the same push.
Step 3 — Observe differences (10 min)
Record what changed in speed, distance, or stopping.
Step 4 — Check fairness (10 min)
Students explain how they kept the test fair.
Step 5 — Make a claim (10 min)
Students explain how mass affected the results.

💬 Discussion Questions

Why should the ramp stay the same in both tests?Changing only one variable makes the comparison fair.
How did the heavier object behave?It may have needed more force to change in the same way.
What counts as evidence here?Specific observations like distance, speed, or stopping behavior.

🚀 Extensions

Extension: Try adding a third mass level and see whether the pattern continues.

👩‍🏫 Parent/Teacher Notes

Teaching move: If students get mixed results, that is okay — focus on careful comparison and evidence, not perfection.

Student Worksheet

Name: ________________________     Date: ________________________

1️⃣ Compare the two versions

ObjectWhat happened?Evidence
Lighter object
Heavier object

2️⃣ Was your test fair? Explain.

🔑 PARENT ANSWER KEY — Detach before giving worksheet to students

Sample Claim

The heavier object’s motion changed differently because it had more mass. Students may describe needing more force or moving a different distance.

✅ What Success Looks Like