Frosty Has been Murdered!
Finding hands on activities to teach about radioactivity and half-lives is always a challenge for chemistry teachers! So today I’m sharing my favorite half-life lab with you!
In a nutshell, students must solve the mystery of Frosty’s murder by collecting data to determine his time of death!
This little CSI lab is easy and inexpensive to prepare, highly engaging, and it helps students gain a little understanding of how carbon-dating works.
One of my students wrote of this activity: “It was a super fun lab that helped me think hard and long about the activity and how to solve it. It really challenged my thinking.”
What more could a teacher ask for?
Frosty Half-Life Lab Summary
Summary: Students will design an experiment to calculate the “half-life” of a melting mini snowman – the time it takes to “decay” (melt) to half its original mass. Thereby solving Frosty’s murder.
Learning Goals:
- Students can design an investigation and collect data to calculate a half-life.
- Students will understand the usefulness of half-lives and their application to radioactive dating in the real world.
Time Required: Around 60 minutes.
Materials Needed:
- Ice or snow – I use this snow cone machine to make my snowmen if there’s no snow out.
- Students Slides for Lab Report (preview below)
- Google Sheets for data collection
- Ring stands with ring clamp
- Funnels
- Beakers
- Graduated Cylinders
- Thermometers
- Hot Plates
- Balances
- Timers
Essential Question(s):
- How can your knowledge of radioactive decay be used to determine the age of a substance?
First, Practice Half-Life Calculations
Prior to the investigation, students need to have a basic understanding of radioactivity and half-lives.
Here are some guided slides that I use to teach that concept during the class period prior to our lab activity. Students simply fill in the blanks, marked in yellow on the student version. (Preview below)
These are digital notes that students keep in their digital portfolio. A new post on digital portfolios coming soon!
How to Set Up
You will need to set up the lab 1 to 3 hours before your class starts.
The prep for this activity is pretty simple, but you do need SNOW! I often make my own “snow” using a snow cone machine like this one!
- Set up a ring stand with iron ring holding a funnel. One for each lab station (groups of 3-4 is ideal for this activity).
- Make one mini-snowman for each lab group.
- Set the snowman in the funnel and place a beaker beneath to catch the water as it melts. (See picture below)
- Provide each lab station with assorted graduated cylinders, a balance, thermometer, hot plate, timer, and any other equipment needed for their investigation. I let students completely design their own experiment, but these are the most commonly used items.
Lab Time!
When students come to class on the day of the half-life lab, I enthusiastically convince them that they get to solve a murder today.
Then we read through the “Introduction” section on the lab report and get to work!
Here is a little preview of the lab report. You can download it free below or submit your email and I will send you both the blank lab report AND a student example/key!
Why I love This Activity
- They have to think HARD, and THEY LIKE IT. Seriously, it’s such a great exercise in critical thinking for students!
- Collaborative student-led inquiry. I love watching my students come together to solve a problem! Each group comes up with their own strategy for solving the mystery and it is MAGIC to watch it happening.
- Cross-curricular math. This activity relies heavily on math skills! But it’s fun!?
- Science skills practice. Solving this mystery really becomes a test in basic science skills like measuring with precision, collecting & analyzing data, graphing, and so much more!
- High engagement. I had a football player stay through his lunch so he could work through his calculations again. That’s how much students love this activity!
How was it?
I would LOVE to hear your feedback for this half-life lab! How did it go? Please share in the comments!
For another fun chemistry activity like this, check out my Chemistry Valentines lesson!
Good luck!