A Popcorn Model for Radioisotopic Dating

Contributor
Susie Welch, Nelia Dunbar, Bill McIntosh, Lynn Heizler
Type Category
Instructional Materials
Types
Lesson/Lesson Plan
Note
This resource, vetted by NSTA curators, is provided to teachers along with suggested modifications to make it more in line with the vision of the NGSS. While not considered to be “fully aligned,” the resources and expert recommendations provide teachers with concrete examples and expert guidance using the EQuIP rubric to adapted existing resources. Read more here.

Reviews

Description

In this activity, leads the students in understanding of half- life,  exponential radioactive decay and how to find the age of the rocks by creating and interpreting a graphs.  Students simulate radioactive decay of Ar-K with kernels and popped corn in a microwave popcorn bag as a “kernelite/popcornium” system. They count the number of kernels and popped corn, plot the “decay” curve of kernelite and the “accumulation” curve of popcornium, and use these curves to establish the “half-life” of kernelite. Then they determine the “age” (popping time) unknown popcorn bag. The learning activity provides the lesson outline, student handout, and links to background information to be used by the instructor.

Intended Audience

Educator and learner
Educational Level
  • High School
Language
English
Access Restrictions

Free access - The right to view and/or download material without financial, registration, or excessive advertising barriers.

Performance Expectations

HS-PS1-8 Develop models to illustrate the changes in the composition of the nucleus of the atom and the energy released during the processes of fission, fusion, and radioactive decay.

Clarification Statement: Emphasis is on simple qualitative models, such as pictures or diagrams, and on the scale of energy released in nuclear processes relative to other kinds of transformations.

Assessment Boundary: Assessment does not include quantitative calculation of energy released. Assessment is limited to alpha, beta, and gamma radioactive decays.

This resource appears to be designed to build towards this performance expectation, though the resource developer has not explicitly stated so.

Comments about Including the Performance Expectation
This activity leads students in developing a graphical model around half-life and radioactive decay by doing an activity. Students plot graph from the generated data and use this data to find the “age” of an “unknown rock” (popcorn bag). This activity effectively covers part of the performance expectation dealing with half life and radioactive decay. However, to more fully address the performance expectation,, this activity needs to further emphasize on the energy transfer and the conversion of proton and neutron (and vice versa) during nuclear processes such as fission, fusion and radioactive decay. This activity has Geoscience connection with finding age of the rocks around PE HS-ESS1-5 and HS-ESS2-3 but needs to further develop to make those connections explicit.

Science and Engineering Practices

This resource appears to be designed to build towards this science and engineering practice, though the resource developer has not explicitly stated so.

Comments about Including the Science and Engineering Practice
Students develop a model for exponential radioactive decay and for calculating half-life by studying the “kernelite/popcornium” system in a microwave popcorn bag. Students then apply mathematical thinking and computations to make a graph to calculate the “age” of an unknown “rock” (popcorn bag). This activity explicitly covers the practice and does not need further modifications. One suggestion to enhance the practice further is to add actual data set of K- Ar decay and compare it with the data that students obtained to explicitly connect the Ar-K decay to popcornium model.

Disciplinary Core Ideas

This resource appears to be designed to build towards this disciplinary core idea, though the resource developer has not explicitly stated so.

Comments about Including the Disciplinary Core Idea
In this activity, students learn about half-life during radioactive decay and its role in radioisotopic dating. Student learn how to find the age of the rocks by analyzing the ratio of popped to unpopped kernels that were popped for different times in a microwaveable popcorn bag. Students plot the abundance of parent and daughter nuclei represented by kernels and popped popcorns. Students then use this graph to calculate the half-life and find the age of an unknown popcorn bag. Students may further analyze the articles and seeing how radioisotopic dating was used in predicting the age and sharing out with the class as review and reinforcement of the core idea.

This resource appears to be designed to build towards this disciplinary core idea, though the resource developer has not explicitly stated so.

Comments about Including the Disciplinary Core Idea
In this activity, students learn about half-life during radioactive decay and its role in radioisotopic dating. Student learn how to find the age of the rocks by analyzing the ratio of popped to unpopped kernels that were popped for different times in a microwaveable popcorn bag. Students plot the abundance of parent and daughter nuclei represented by kernels and popped popcorns. Students then use this graph to calculate the half-life and find the age of an unknown popcorn bag. Students may further analyze the articles and seeing how radioisotopic dating was used in predicting the age and sharing out with the class as review and reinforcement of the core idea.

Crosscutting Concepts

This resource was not designed to build towards this crosscutting concept, but can be used to build towards it using the suggestions provided below.

Comments about Including the Crosscutting Concept
Students build a model to understand half-life as the time in which half the radioactive nuclei disintegrate. This is accomplished by using the data obtained from modeling radioactive decay with popping the microwave popcorn. Using this graph, students then apply the pattern to find the age (time taken) of an unknown rock ( unknown bag of popcorn). The crosscutting concept of patterns may be further enforced by having students do some review problems with half-life based in real life context.

Resource Quality

  • Alignment to the Dimensions of the NGSS: This grade appropriate learning activity provides opportunity to engage students in three dimensional learning around the disciplinary core idea of radioactive decay and half-life. Having students develop a mathematical model for half-life as an exponential decay with “kernelite/popcornium” system is interesting. Students develop and apply the crosscutting concept of system and system models to find the age of an unknown rock (popcorn bag). This learning activity brings relevance by incorporating the phenomenon of radioisotopic dating in finding the age of the rock and the history of the earth. Prefacing this lesson with the article linked below will help in connecting radioactive dating with fossil discovery. https://science.howstuffworks.com/environmental/earth/geology/dinosaur-bone-age.htm

  • Instructional Supports: This lesson has excel spreadsheets to record data and provides worksheets where technology may not be easily accessible to students. All worksheets are clear and well developed. More clarity around setting up the activity for the teachers would be helpful.

  • Monitoring Student Progress: This activity does not have formative or summative assessment. Including a formative assessment in form of finding the “age” of a “rock” (partly popped bag of popcorn) using the models developed by the students will assess student understanding. A good place for this formative assessment will be after the students have plotted the graph for kernelite/popcorn system.

  • Quality of Technological Interactivity: The excel worksheet is well developed and students can enter data directly into this spreadsheet, but there is limited interactivity.