---
title: "AP Physics 1 Science Practice 3: Questioning and Argumentation"
description: "Learn AP Physics 1 Science Practice 3: design experiments, apply laws to make claims, and justify claims with evidence. Subskills 3.A, 3.B, and 3.C explained."
canonical: "https://fiveable.me/ap-physics-1-revised/science-practices/science-practice-3-scientific-questioning-and-argumentation/study-guide/enk6nBXsi7mRkILIa1Cl"
type: "study-guide"
subject: "AP Physics 1"
unit: "Science Practices"
lastUpdated: "2026-06-17"
---

# AP Physics 1 Science Practice 3: Questioning and Argumentation

## Summary

Learn AP Physics 1 Science Practice 3: design experiments, apply laws to make claims, and justify claims with evidence. Subskills 3.A, 3.B, and 3.C explained.

## Guide

## Overview

[AP Physics 1](/ap-physics-1-revised "fv-autolink") Science Practice 3: Scientific Questioning and Argumentation is the practice where you design experiments, make physics claims using laws and models, and back those claims with evidence. You do three things here: build a procedure that answers a scientific question, apply the right principle to state what should happen, and justify your reasoning with data, diagrams, or physics laws.

This practice is one of the three [science practices](/ap-physics-1-revised/science-practices "fv-autolink") that run through every unit of the course, from [kinematics](/ap-physics-1-revised/unit-1 "fv-autolink") to fluids. It shows up on both the multiple-choice and free-response sections, so you will use it constantly whether you are picking a correct claim on the MCQ or writing a justification on an FRQ.

## What Science Practice 3: Scientific Questioning and Argumentation Means

The grouping description sums it up: describe experimental procedures, analyze data, and support claims. Think of it as the "argue your case" practice. You are not just calculating a number. You are deciding what experiment to run, what conclusion the physics supports, and why your evidence proves it.

Three subskills live here:

- **3.A** Create experimental procedures that fit a given scientific question. (FRQ only)
- **3.B** Apply an appropriate law, definition, theoretical relationship, or model to make a claim. (MCQ and FRQ)
- **3.C** Justify or support a claim using evidence from experimental data, physical representations, or physical principles or laws. (MCQ and FRQ)

## What This Practice Requires

Each subskill asks for a slightly different move.

**3.A: Design a procedure.**
Given a question like "how does [mass](/ap-physics-1-revised/key-terms/mass "fv-autolink") affect a [system](/ap-physics-1-revised/unit-2/1-systems-and-center-of-mass/study-guide/nielAWaOcpzSSLLO "fv-autolink")'s oscillation period," you describe what you would measure, what you would vary, what you would keep constant, and how you would use the data. A strong procedure can actually be carried out and produces data that answers the specific question asked.

**3.B: Apply a principle to make a claim.**
You pick the law or model that fits the situation and state what it predicts. Example: a [force](/ap-physics-1-revised/unit-2/2-forces-and-free-body-diagrams/study-guide/jQ2Obd0dAU4QiTPN "fv-autolink") changes only the horizontal velocity of an object, so the [net force](/ap-physics-1-revised/key-terms/net-force "fv-autolink") must point horizontally. You are matching the physics to the scenario and stating the result.

**3.C: Justify the claim with evidence.**
You connect your claim to specific support. That support can be experimental data, a graph or diagram, or a physics principle. The key is naming the reason. "The [speed](/ap-physics-1-revised/key-terms/speed "fv-autolink") is less because of [conservation of linear momentum](/ap-physics-1-revised/key-terms/conservation-of-momentum "fv-autolink")" is a justification. "The speed is less" alone is not.

## Skills You Need for This Practice

- Identify the scientific question being asked and what variable it targets.
- Choose independent, dependent, and controlled variables when designing a procedure (3.A).
- Recognize which law or model applies to a scenario: [Newton's laws](/ap-physics-1-revised/unit-8/3-fluids-and-newtons-laws/study-guide/PbLGJiZX2gzaitf5 "fv-autolink"), [work-energy theorem](/ap-physics-1-revised/key-terms/work-energy-theorem "fv-autolink"), conservation of momentum or energy, buoyancy, SHM relationships, and more (3.B).
- Read evidence from graphs, free-body diagrams, energy bar charts, and data tables (3.C).
- State a clear cause-and-effect reason that ties your claim to a principle, not just to a result.

## How It Shows Up on the AP Exam

The exam has 40 multiple-choice questions and 4 free-response questions, each section worth 50 percent.

**On multiple choice:**
- Only 3.B and 3.C are tested (3.A is FRQ only).
- 3.B questions ask you to choose the claim or representation that the physics supports. For example, picking the [force diagram](/ap-physics-1-revised/key-terms/force-diagram "fv-autolink") that matches given velocity-versus-time components, or comparing [pendulum](/ap-physics-1-revised/key-terms/pendulum "fv-autolink") and spring periods on a new planet.
- 3.C questions pair a claim with a reason, and you select the option where both the claim and the justification are correct. Wrong choices often have a right claim but a wrong reason, or a right reason attached to a wrong claim.

**On free response:**
- All three subskills can appear.
- 3.A shows up most directly in the Experimental Design and Analysis question (Question 3), where you describe a procedure.
- 3.B and 3.C appear across all four FRQ types whenever you make a claim and justify it. For example, deciding whether a [rolling](/ap-physics-1-revised/unit-6/5-rolling/study-guide/Ezw0DtDmEDYrpqzr "fv-autolink") disk or a [sliding](/ap-physics-1-revised/unit-2/7-kinetic-and-static-friction/study-guide/iK44HM4UlsWqRPfS "fv-autolink") block reaches the bottom first, then justifying with energy reasoning.

This is practical advice based on the exam structure, not an official scoring rule.

## Examples Across the Course

Science Practice 3 looks different depending on the unit, but the moves stay the same.

- **Unit 2, Forces (3.B):** An object's velocity components change a certain way over time. You apply [Newton's second law](/ap-physics-1-revised/unit-2/5-newtons-second-law/study-guide/FizcgPbKTypwBNrG "fv-autolink") to claim which force diagram fits. The net force [direction](/ap-physics-1-revised/unit-1/4-reference-frames-and-relative-motion/study-guide/iTcYEEULwbQlf2nW "fv-autolink") must match the direction of acceleration.
- **[Unit 3](/ap-physics-1-revised/unit-3 "fv-autolink"), Work and Energy (3.C):** A [constant force](/ap-physics-1-revised/key-terms/constant-force "fv-autolink") pushes a block from 0 to 50 cm, then 50 to 100 cm. You claim the kinetic energy change is equal in both intervals and justify it with the work-energy idea that the same force over the same distance does the same work.

- **Unit 4, [Momentum](/ap-physics-1-revised/unit-4/1-linear-momentum/study-guide/aEYIGw4MVE0g5Zrb "fv-autolink") (3.C):** A block is dropped onto a sliding block and sticks. You claim the speed decreases and justify it with conservation of linear momentum, not conservation of mechanical energy.
- **Unit 5 or 6, Rotation (3.B and 3.C):** A disk rolls down a ramp while an identical-height ice block slides down a frictionless ramp. You claim which takes longer and justify it using energy distribution, since the rolling disk puts some energy into rotation.

- **Unit 7, Oscillations (3.B):** A pendulum and a spring both have a 1 s period on Earth. On a planet with the same diameter and twice the mass, you claim the pendulum period gets shorter while the spring period stays the same, because pendulum period depends on g and spring period does not.

## How to Practice Science Practice 3: Scientific Questioning and Argumentation

- For every claim you make, write a one-sentence "because" that names a law or model. Train yourself to never leave a claim unsupported.
- When you see an MCQ with claim-plus-reason answers, check the claim and the reason separately. Eliminate any option where either half is wrong.
- For 3.A practice, take any lab idea and list your variables: what you change, what you measure, what you hold constant. Then ask if the data would actually answer the question.
- Build a mental list of which principle governs which situation. Momentum for collisions, energy for distances and speeds, Newton's laws for forces and acceleration, buoyancy for floating objects.
- After solving any problem, restate your answer as a claim and ask "what evidence proves this." That is exactly what 3.C wants.

## Common Mistakes

- **Stating a claim with no reason.** "The speed decreases" earns the claim but not the justification. Always name the principle.
- **Matching the wrong principle to the situation.** Using conservation of mechanical energy in a sticking collision is a classic error. Inelastic collisions conserve momentum, not mechanical energy.
- **Designing a vague procedure.** Saying "measure the motion" does not answer the question. Specify the variable you vary and the one you measure.
- **Forgetting controlled variables in 3.A.** If you change two things at once, your data cannot answer the question.
- **Confusing a result with evidence.** Citing the answer you got is not justification. Cite the law, graph, or data that leads to that answer.

## Quick Review

- Science Practice 3 is about designing experiments and arguing claims with evidence.
- **3.A** (FRQ only): build a procedure that fits a scientific question.
- **3.B** (MCQ and FRQ): apply a law or model to make a claim.
- **3.C** (MCQ and FRQ): justify a claim with data, representations, or principles.
- On MCQ claim-plus-reason items, both the claim and the reason must be correct.
- The skills are identical across units. Only the physics principle changes.
- Habit to keep: every claim gets a "because" tied to a law, model, or piece of evidence.