Not One Atom Lost

About this resource

Burn paper, and the ash left behind weighs much less. Burn a fluffy pad of steel wool, and it gets heavier! How can burning make one thing lighter and another heavier — and where does the extra mass come from? In a chemical reaction, atoms trade partners — but not one atom is made or lost, so mass is conserved. In this one-week, 5-level Conservation of Mass in Chemical Reactions unit for middle school science (NGSS MS-PS1-5), students investigate a real mystery, then use their evidence to crack the case.

Not One Atom Lost is part of Science Unlocked, a series of mystery-driven lesson sets. Every set opens with a real, surprising phenomenon, builds the science one level at a time, and ends with students solving the mystery in a claim-evidence-reasoning (CER) write-up.

Topics: conservation of mass, law of conservation of mass, conservation of matter, chemical reactions, claim evidence reasoning (CER), science phenomenon, review games.

What's included

• Teacher Deck (92 slides, PowerPoint). Answers are highlighted on the slides. Speaker notes tell you what to say and do, what to watch for, and how to support students or push GT students further. Prep slides and answer keys are hidden, so they skip during a slideshow.
• Interactive Student Deck (54 slides, PowerPoint + PDF). Students type in boxes, drag cards and check marks, and rate their confidence. Assign one copy per student in Google Classroom or your LMS.
• Google Slides versions of both decks. Click a button in the Google Slides Links PDF to make your own copy in Google Drive.
• Teacher Guide (25-page PDF). The standard, a week at a glance, a materials list, misconceptions to watch for, a run-of-show for every level, answer keys and sources.
• Student Printable (18-page PDF + a low-ink greyscale copy). The same tasks on paper in 12 pt type, for students without devices, sub days, or anyone who learns better with a pencil. Slide numbers match the Student Deck.
• Self-grading digital activity. SCORM 2004 and SCORM 1.2 packages for an LMS that accepts SCORM uploads, a web package, and a single HTML file that opens in any browser. Notes, sorts, matches, tables and multiple-choice items grade themselves, and students get a copy-and-paste backup of their work. A 2-page teacher quick start is included.
• Two whole-class review games that open in any browser: a Jeopardy-style game (6 categories, 30 clues) and Trashketball, where teams answer on whiteboards and then shoot for points.
• Kahoot! and Blooket import files. 48 review questions, one file per level plus an all-levels file, with a printable answer key.
• Start Here guide, HTML & SCORM how-to guide and Terms of Use, so you know which file to open first.

The 5 levels (about one 45–50 minute class each)

1. Burned but Heavier? Atoms, elements, molecules, gases are matter, reading atom models. Key activities: Steel wool mystery, Read the Molecules model, Matter sort.
2. Atoms Regroup. Chemical reactions = atoms regroup into new substances. Key activities: Rocket Fuel model, Build It (gas stove), Count the Atoms.
3. Sealed Bottle Lab. Closed vs. open systems, mass in a reaction. Key activities: Sealed Bottle Showdown lab, atom count, Lab Conclusion CER.
4. Count Every Atom. Law of conservation of mass, open systems can gain or lose mass. Key activities: Lavoisier story, steel wool demo, model, Up/Down/Same sort, Model Detective.
5. Crack the Case. Stretch HS-PS1-7: mass math, the mole. Key activities: Mass Math, Stretch CER, final Crack the Case CER.

Built for real classrooms

• Every level follows the same routine: "I can" targets with a confidence check, a warm-up, copy-it notes with a word bank, hands-on practice, a checkpoint students must pass to unlock the next step, and an exit ticket. A 10-item Mini Quiz wraps up the week.
• Level 1 opens with a Power-Up on the earlier-grade ideas this standard builds on (2-PS1-3, 5-PS1-1, 5-PS1-2, 5-PS1-4).
• The last level includes a high school Stretch (HS-PS1-7) that every student tries and advanced students can take further.
• Hands-on lab (The Sealed Bottle Showdown). Student materials list: 2 plastic soda bottles (500 mL), caps: OPEN and CLOSED; Vinegar: 30 mL per bottle; Baking soda: ¼ teaspoon per bottle; 2 tissue squares; Digital scale (0.1 g); Graduated cylinder, funnel. Safety notes are on the slides and in the Teacher Guide.
• Support is built in: word banks, sentence starters and support notes on the slides, plus GT extensions.

Standards

• NGSS MS-PS1-5: Develop and use a model to describe how the total number of atoms does not change in a chemical reaction and thus mass is conserved. (Kentucky 7-PS1-5 uses the same wording.)
• SEP: Developing and Using Models · DCI: PS1.B · CCC: Energy and Matter
• Stretch: HS-PS1-7
• CCSS connections: 6.RP.A.3, MP.2, MP.4, RST.6-8.7

Try the digital activity first

• Not sure the self-grading activity will work in your LMS? Download the FREE HTML & SCORM Sample and test it with your students before you buy.

Save with a bundle

• Matter & Chemical Reactions (5 sets)
• Middle School Physical Science + Engineering (23 sets)
• Science Unlocked Mega Bundle (all 89 sets)

Teach next

• Pencil or Diamond? (MS-PS1-1)
• The Fatberg Files (MS-PS1-2)
• The Nylon Rush (MS-PS1-3)
• The Vanishing Spoon (MS-PS1-4)

More from Mystery Lab Learning

• See every Science Unlocked set, and follow to hear when new ones are added, at Mystery Lab Learning.

Good to know

• The illustrations in this resource were created with AI image tools, and AI tools helped draft the lesson text. Every slide, answer key and lab step was then fact-checked against the sources listed in the Teacher Guide and proofread.
• Kahoot!, Blooket, Jeopardy!, Google Slides and PowerPoint are trademarks of their owners. This resource is not affiliated with or endorsed by them.
• License: one teacher, for use with their own students. Please buy an additional license for each colleague who uses it.