Radioactive Decay Lab – Geologic History, Age of Fossils, Worksheets, Activity

Get ready to make radioactive decay something your students can actually see, touch, and model instead of just memorize.

In this hands-on lab, students use M&Ms (“Candium”) and split peas (“Greenium”) to simulate how unstable isotopes break down over time. Through repeated “half-life shakes,” they collect real data, track parent vs. daughter atoms, and graph the changes to visualize exponential decay in action. Students then connect their results to how scientists use radioactive dating to determine the age of rocks, fossils, and Earth’s history.

This is not just a novelty candy lab. It’s a structured scientific investigation where students build, analyze, and interpret data the way real geoscientists do.

Why You’ll Love This Lab:

• Highly engaging and memorable, students stay focused because they are actively modeling decay
• Low-prep and easy to run with simple, accessible materials
• Strong real-world connection to radiometric dating and Earth’s geologic timeline
• Builds data analysis and graphing skills in a meaningful context

What’s Included?

• Student Lab – A step-by-step, student-friendly investigation with data collection, graphing, and analysis questions that guide understanding of radioactive decay and half-life.
• Instructor Answer Key – A complete, clearly explained key to support grading, instruction, and classroom discussion.
• Teacher Guide – A full implementation guide with pacing, NGSS alignment, prep checklist, differentiation supports, misconceptions, classroom management tips, and more to make setup and instruction smooth and stress-free.

What You’ll Need:

• M&Ms
• Split peas
• Container or cup
• Paper towels

This lab turns an abstract concept like half-life into something students can physically model and actually understand. It’s perfect for Earth science or chemistry classrooms looking for a meaningful, hands-on way to teach radioactive decay and radiometric dating without the overwhelm.

Grade Levels: 8th – 12th
Total Pages: 21
Teaching Duration: 65 Minutes

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Jessica