7th Grade Science : Unit #7 - Geologic Time : Lesson #3

Radioactive Dating

Objective: Students will be able to explain how scientists determine the ages of rocks using radioactive decay.
Standards: MS-ESS1-4 SP4 XC-SC-MS-1
Subject(s): Science
60 minutes
1 Hook - 5 minutes

To introduce the idea of radioactive decay and carbon dating, I play a video clip from Nova "Hunting the Elements". As the video comes to an end, I pose the question, "Why is Carbon-14 useful to determine the age of organic remains?"

2 Explore - 35 minutes

I tell the students that they will now become archaeologists as they play with the PhET simulation "Radioactive Dating Game". I ask the students to divide themselves into partners, and request that one partner to get a computer, while the second partner gets the record sheet they will use. Although students could work through the simulation individually, I prefer partnerwork to foster discussion among students, encouraging scientific discourse (SP7). 

In this video I walk you through using the simulation.


As the students work on the simulation they are visualizing how stability and change in natural or designed systems can be constructed by examining the changes over time (CCC Stability and Change), as well as analyzing and interpreting data (SP4). here are some examples of student work (SW1SW2).

Using simulations

Teaching radiometric dating by telling the students what it is, and how it works, at best reaches the students at a surface level of understanding. However, when the students actually get to play around with how it works and experience it first hand, they become much more interested.

Although I would love to be able to actually perform radiometric dating in my classroom, I lack both the materials and expertise. So what is the next best thing? Using a simulation! Simulations encourage deep learning. Students think of online simulations as mini-games but, as they work through the different tasks, they are working like scientists, confirming or dismissing hypotheses. They are paying close attention to the inner workings of the concept of radiometric dating and applying what they are learning to the "real" work of dating the different items. 

The key to successfully using simulations in the classroom lies in finding the appropriate resource. Phet colorado has many simulations in a wide range of math and science topics. They have become my go-to place for quality simulations, and only when I don't find my topic there do I go searching down the "internet rabbit hole".

3 Closure - 5 minutes

To close this lesson I ask that students write, on Edmodo, what was the most interesting thing they learned in today's lesson. The review of this responses allows me to gauge not only how the lesson went, but also how the simulation engage/did not engage the students. Here's a sample of what they answered.