Little Lab Coats

Testing One Change at a Time

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

📚 Grade: 4th Grade⏱️ Duration: 45–60 minutes🔬 Subject: Physical Science — Energy & Motion

📋🎯

Scientists learn more from motion tests when they change one variable and keep the rest controlled.

📋 NGSS Standard:
4-PS3-1 — Use evidence to construct an explanation relating the speed of an object to the energy of that object. / 4-PS3-3 — Ask questions and predict outcomes about the changes in energy that occur when objects collide.

🎯 Learning Objective

Students will plan and run a fair Energy & Motion test that changes one variable and uses evidence to compare results.

💡 The Big Idea

A fair test changes one important variable at a time so the evidence is easier to trust and explain.

🔬 The Science

Science Snapshot

Controlled testing helps reveal which variable actually changed the motion or energy outcome.

What is happening?

Fair tests change one variable at a time so students can tell what actually caused a result. In energy and motion lessons, that might mean changing only ramp height, only mass, or only surface texture.

Why it works that way

If several things change at once, the evidence becomes muddy because there is no clear cause-and-effect link. Controlled tests are an important scientific tool because they reduce confusion and make comparisons trustworthy.

Look for this in the lesson

Students should be able to name the variable they changed and the variables they kept the same. That planning step is what turns a fun build into a real investigation.

Ask while you read: Which variable are you testing, and how are you keeping the rest fair?

📦 Materials

🏠 Household Items to Gather

Any tested object from prior lessons
Ramp, surface materials, or collision targets
Ruler or tape measure
Worksheet and pencil

📋 Printables

Student worksheet page from this lesson

🧪 Investigation

Step 1 — Choose one variable (10 min)
Select one thing to change: speed, surface, or collision setup.

Step 2 — Name the controls (10 min)
List what will stay the same in every test.

Step 3 — Run at least two trials (10 min)
Carry out the comparison and record what happened.

Step 4 — Look for a pattern (10 min)
Decide whether the changed variable affected the result.

Step 5 — Defend the fairness (10 min)
Explain why the test gives useful evidence.

💬 Discussion Questions

What variable did you change?Students should name one specific feature such as ramp height or surface type.

What did you keep the same?The same object, same release method, or same target can all be controls.

Why does fairness matter in science?It helps you trust that the changed variable caused the result.

🚀 Extensions

Extension: Trade test plans with a partner or family member and check whether the plan really changes only one variable.

👩‍🏫 Parent/Teacher Notes

Teaching move: If students want to change too many things, have them circle the one question they most want to answer first.

Misconception to catch: “More complicated” does not mean “more scientific.” Clear comparisons are stronger.

Student Worksheet

Name: ________________________ Date: ________________________

1️⃣ Plan your fair test

What will I change?	What will I keep the same?	What evidence will I collect?

2️⃣ What pattern did you find?

🔑 PARENT ANSWER KEY — Detach before giving worksheet to students

Sample explanation

Strong answers name one changed variable and several controlled parts of the setup. Students should collect specific evidence and explain why the comparison was fair.

✅ What Success Looks Like

Student clearly identifies the variable and controls.
Student records usable evidence from the test.
Student uses the fair-test idea to strengthen the explanation.