Radioactive Decay

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Objective

Students will be able to model different types of nuclear decay.

Big Idea

Nuclear decay results from unstable nuclei; to stabilize, atoms emit energy, particles, or both.

Introduction

Unit Overview: This unit, called Passion, Power, and Peril, is an inter-disciplinary unit between two classes—English and Chemistry. In Chemistry class, students will learn about nuclear chemistry, but they will also research a specific aspect of the nuclear power industry. They will use this research in three ways. First, they will write a one-page paper for a Chemistry grade that explains how nuclear chemistry connects to the research topic. Second, students will write an informative/explanatory research paper that answers your research question by showing the complexity of the issue for an English grade. Finally, students will use their research and writing to create a piece of artwork for a multimedia art display designed to challenge the audience with weighing the costs and benefits of nuclear technology.

In this process we would like students to consider the following questions: How does society evaluate costs and benefits of a technology?  What are the costs and benefits of nuclear power plants?

Lesson Overview: In this lesson students read about nuclear decay and take notes. They then take what they learn to model different types of decay using their bodies as nucleons.

This lesson aligns to the NGSS Disciplinary Core Idea of 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 by giving the students the chance to use what they learn about nuclear decay in the modeling process.

It aligns to the NGSS Practice of the Scientist of Developing and using models because students use a model to better understand decay, and when the model does not look right they get the chance to fix the model.

It aligns to the NGSS Crosscutting Concept of Energy and Matter by showing that in nuclear processes, atoms are not conserved, but the total number of protons plus neutrons is conserved.

In terms of prior knowledge or skills, students should have an understanding of nucleons (protons and neutrons).

The materials needed for this lesson include enough pieces of paper with the words proton and neutron written on them for so that every student can have one, and one paper each for the words positron, beta particle, and gamma radiation.

 

 

 

Do Now/Activator

10 minutes

Do Now: I start class by asking students to copy the table for the Nuclear Decay Notes that I project on the board.

I reason that this is a good way to start class because students will be tasked with filling in the table during the first part of class and this gives every student access to today’s lesson with a task that they can do independently.

Activator: I ask students to access prior knowledge by asking them why a nuclear bomb explosion would continue to harm life long after the explosion. After some discussion, students answer with the word radiation.

I have chosen this approach because I want to ensure that there is a real world connection to my lesson. I will note at the end of the lesson that nuclear power plants also have issues related to radioactivity and human health.

Mini-lesson

15 minutes

Mini-lesson: The first thing I do is ask students about what they know about radioactivity. They have heard that it has something to do with cancer, and superheroes. I note that this is a good time to get an overview of what radiation is with a video.

We then discuss the video. I emphasize that radioactivity is a natural process in which an unstable atom gives of energy and often times particles in order to become more stable. There are different types of particles that can be emitted. When these particles or energy travels through space, this is known as radiation.

This instructional choice reflects my desire to give students a visual image of what radioactivity looks like so that when they are reading and taking notes they have some schema upon which to hang the ideas they are reading about.

Application

25 minutes

Student Activity: Students read sections in their text book. A similar reading on the web for alpha, gamma, and beta radiation can be found on this website, while positron emission information can be found here in the first slide. While students are reading they are taking notes in the graphic organizer they made at the beginning of class.

I want students learning in this way because I believe that they need many opportunities over the course of the year for reading scientific textbooks. This skill is something with which they should be very comfortable with by the time they are in college, and so usually, given a choice between lecture and students grappling with text, I choose the latter.

When students are finished taking notes, I project a student's notes on the screen so that all students can be sure to have recorded the correct information.

Once students have the necessary notes, I hand out pieces of paper that have the words proton, neutron, positron, beta particle, or gamma radiation. I then explain that they are now going to model the different types of nuclear decay. For each type of decay, I remind students about what the different types of decay look like, they then do the model, and then if necessary I ask them to revise the model to make it a little more realistic. During the modeling students role-play nucleons in a nucleus, physically moving to represent particle ejection. 

In the first video, in which students learn how to learn how to model decay, there is a fair amount of revision that has to happen. However, the final alpha decay model was good. In these videos students also model beta decay, gamma decay, and positron emisssion.

 

Debrief

10 minutes

To wrap this lesson up I project a blank nuclear decay graphic organizer that we used at the start of class. I ask students to turn and talk about each of the types of nuclear decay. They can look at their notes if they need help. I ask that they pay attention to what they learned and what they still need to study, and they should study everything for homework with special attention to the items they needed to peek back at their notes.

Ending class this way allows me to walk around and listen to what students learned and did not learn. They definitely have the gist down—particles are being emitted, and protons and neutrons change for every type of decay we studied except for gamma decay. They do need to fill in the details, but they have an outline they will be able to build off of.

The next time I do this I would divide students into two groups and ask them to compete against one another to see who can best model each of the types of decay. While I was pleased with the overall result, I think that students are capable of more leadership, and this responsibility would increase their own learning.