A two-part hands-on STEM companion to the Launch Control breakout. Part A proves conservation of mass (Lock 1 & 3). Part B tests Newton's Second Law, a = F ÷ m (Lock 2).
🎯 The problem (define)
Part A — Fuel check: the launch team must prove that a chemical reaction doesn't lose mass. Design a sealed system that lets a fizzing reaction happen while you measure mass before and after. Part B — Thrust check: engineers must predict how added cargo changes a rocket's acceleration. Build a straw rocket and test how payload mass changes how far/fast it flies at a fixed launch push.
Anchor questions: If atoms are only rearranged, why should the sealed mass stay the same? And if a = F ÷ m, what should more mass do to the launch?
🧰 Materials (per team of 2–4)
Part A: a zip-seal bag, baking soda, vinegar, a small cup, a balance/scale
Part B: a straw, paper, tape, a slightly wider straw or launcher, paperclips (payload mass), a tape measure
This recording sheet and a pencil
⚠️ Safety: wear goggles for Part A. Do not over-fill or force a bulging bag — open it away from faces. Follow your teacher's TEA-approved lab safety rules.
🔁 The engineering design process
Define the problem: prove mass is conserved, then test how mass changes acceleration.
Imagine & brainstorm: how will you keep the reaction fully sealed? What payloads will you test?
Plan: predict the after-reaction mass (Part A) and rank your payloads by expected distance (Part B).
Create: build the sealed bag (keep vinegar in the cup until sealed) and the straw rocket.
Test: mass the sealed bag before and after the fizz; launch the rocket with 0, 1, and 3 paperclips, measuring distance each time (repeat trials).
Improve: if the bag lost mass, find the leak and reseal; refine the rocket fins so only mass is changing between launches (a fair test).
📊 Record your data
Part A — Conservation of mass
Mass BEFORE (g)
Mass AFTER (g)
Difference (g)
Sealed bag
A difference near zero is your evidence: atoms rearranged, none escaped. 8.6(E)
Part B — a = F ÷ m
Payload (paperclips)
0
1
3
Flight distance (cm)
Same launch push (force), more mass → shorter/slower flight (less acceleration). 8.7(A), 8.2(B)
🗣️ Explain it — Claim, Evidence, Reasoning (CER)
Claim — Was mass conserved? How did payload mass affect the flight?
Evidence — Your two data tables.
Reasoning — Use atoms rearrange, sealed system, conservation of mass, and a = F ÷ m to explain why. (In a sealed system no atoms leave, so mass is unchanged; with fixed force, more mass means less acceleration.)
🚀 STEM career highlight — Aerospace / Propulsion Engineer & Chemical Engineer. These engineers design rocket fuels and predict how a vehicle's changing mass (as fuel burns) affects its acceleration — the exact two ideas you tested. (Labor data: O*NET & the Texas Workforce Commission; 8.4(C) investigate STEM careers.)
🧩 Extend it: A real rocket loses mass as it burns fuel — so with steady thrust its acceleration increases over the flight. Ask students to connect that to both Lock 1 (the atoms/mass are conserved in the whole system, including exhaust) and Lock 2 (less mass → more acceleration).
TEKS aligned to this challenge
8.6(E) conservation of mass · 8.7(A) Newton's Second Law · 8.1(B) design solutions · 8.1(G) develop & use models · 8.2(B) analyze data · 8.2(D) evaluate designs · 8.4(C) STEM careers. Cross-curricular: Math (differences, averages of trials, ratios), ELAR (CER writing). Aligned to, not reproduced from, the official TEKS — confirm before adoption.