Students will investigate Newton’s 2nd Law of Motion by testing how changing the mass carried by a balloon rocket affects its acceleration. Using a taut string track, a straw, a balloon, and removable mass clips, students run repeated launches to measure travel time and calculate average speed. Through structured trials, data recording, class averaging, graphing, and a CER, students discover how added mass changes motion and why unbalanced forces create different accelerations.

Learning Targets

• Plan and carry out a controlled investigation with repeated trials
• Record travel times and calculate average speed using v=d/t
• Graph class averages to compare how mass affects acceleration
• Construct a CER explaining the relationship between mass and acceleration using Newton’s Second Law
• Identify variables, maintain controls, and improve investigation quality

What’s Included

• Teacher Guide: Setup diagrams, safety notes, timing tips, and background on Newton’s 2nd Law (F = ma). Includes guidance for standardizing balloon size, launch technique, string track length, and mass attachment to ensure fair comparisons.
• Student Packet: Hypothesis prompt, variables identification chart, build/setup instructions, 3-trial data table per mass level, average speed calculations, comparison table, graphing task, and structured CER response.
• Class Data & Graphing Pages: Class totals chart, average-speed bar graph template (“Average Speed vs Added Mass”), labeled axes lines, and a caption prompt requiring students to identify which mass traveled fastest using numerical evidence.
• Analysis & Answer Key: Expected trends (speed decreases as mass increases), sample calculations, reasoning examples, possible error sources, and a complete model CER paragraph grounded in Newton’s Second Law.
• Rubric: Assesses experimental design, data accuracy, graph quality, CER strength, and teamwork/safety—fully aligned with middle-school science practices.
  

Why Teachers Love It:

• Easy prep — only balloons, tape, straw, string, and small masses
• Highly engaging with a clear visual difference between trials
• Builds strong lab-skills: identifying variables, consistency control, and repeated trials
• Perfect introduction to forces, acceleration, and unbalanced forces
• Graphing + CER require true evidence-based reasoning
• Ideal for stations, intro physics, engineering challenges, or sub-friendly lessons

➡️ You can get this STEM as well as all my other ones in this series inside my STEM Investigations Growing Bundle. As more labs are added, the price will increase. CLICK HERE to have a look

Best For

Physical Science (forces, motion, inertia), lab skills, graphing, CER writing, introductory Newton’s Laws, or sub-friendly science explorations.

Materials Needed

Index cards, coins/washers/bolts (various masses), a cup, a ruler, student lab sheet (included), calculator or percent chart. Optional: scale, stopwatch, high-speed video.

Estimated Timing:

1 class period for setup → trials → percent success → class graph. Add 20–30 minutes for CER writing, discussion questions, and error analysis.

➡️ You can get this activity inside my STEM Investigations Growing Bundle.

I also have the following STEM Labs in My Store:

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• Newton's Second Law of Motion STEM Lab - Balloon Rocket

NGSS alignment

MS-PS2-2, MS-PS2-1 (forces & motion, Newton’s 1st Law)

Practices: Planning & Carrying Out Investigations; Analyzing Data; Using Mathematics & Computation; Constructing Explanations; Argument from Evidence

Assessment

Use the included rubric to score environment understanding, adaptation quality and plausibility, scientific accuracy, CER strength, and class data/graph work.