In this lesson students explore the NGSS Performance Expectation 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. As an introduction to this unit students answer a series of questions about nuclear power and radioactivity that help uncover prior knowledge and establish curiosity about nuclear chemistry.
The process of answer the survey helps students to engage in the NGSS Practice, Developing a model. As they progress through this lesson they will create a mental model that can be used throughout the unit as a scaffold for building curiosity and understanding about nuclear chemistry. As a result of the survey students should begin to see that the Crosscutting Concept of Energy and Matter is an underlying theme in this unit. This will be accomplished by students being asked questions about nuclear power and radiation.
As an introduction to nuclear chemistry I like to have my students think about their views of radioactivity, nuclear power and the impact it has on the world we live in. At the beginning of class I have my students pick up what I call a “nuclear survey” (nuclear survey key) which is a list of questions about what they know about nuclear energy, nuclear weapons, radioactivity and whether or not they are dangerous or beneficial.
After picking up the survey, I instruct them to answer all the questions to the best of their ability in 10 minutes and circle 5 of the answers that they are most confident in and square 5 of the answers that they are most uncertain about (called a 5 and 5).
The goal of the survey is to get students to think about nuclear chemistry while building an understanding that much of the discussion they hear about nuclear chemistry in everyday contexts includes misconceptions that has been developed as a result of television, propaganda and lack of knowledge.
As they work on the survey, some of their misconceptions are apparent as when many answer the question about how superheroes (such as Spiderman) get their powers, or when one student states that gamma radiation is okay because it doesn't kill, it only causes mutations.
After 15 minutes of working on the survey I have my students get into groups of four (established by lab tables) and perform a fishbowl that has each student share their 5 and 5 with the group.
Fishbowl Procedures and roles:
My students are used to the procedures that are involved in performing a fishbowl; however, the first time they performed this activity it required a little guidance. A good way to do this is to provide them 3 minutes per cycles, have them stop when completed and wait to be instructed to shift roles.
The fishbowl takes about 10-15 minutes. After each group has completed the cycle we summarize the activity with each group sharing 2 thoughts with the class. I instruct students that the last person to be the reader will be the group spokesperson that shares with the class and each group must report something different to the class. I randomly pick groups to respond so that no group has an advantage when responding.
The purpose of sharing out is to observe any misconceptions that are present so that the process of new learning can occur. Possible misconceptions that still might be present is that all radiation is bad and that all countries have nuclear bombs.
After each group shares with the class one thing they are certain about and one uncertainty, I will go over the true false so they can see how close they were to being correct. The two questions that provide the biggest misconception are "microwaves give off nuclear radiation", and "I get some nuclear radiation all the time". Most of the questions, including these two will be discussed and clarified throughout the unit. There may not be specific lessons on each of the survey questions, but throughout the unit students ask questions based on curiosity which will be discussed when brought up.
After completing the survey I like to provide students with a brief introduction to the concept of radiation by showing BrainPOP: Radioactivty. This short video exposes students to what it means when something is radioactive. In addition, they learn about unstable atoms and how they can turn into completely different atoms with different properties by decaying. Plus, they see what kinds of dangerous rays or particles radioactive decay can create and learn about how radioactivity can be both helpful and harmful to humans.
BrainPOP requires a subscription ($6.99/mo), but I have provided an alternative YouTube video that can be used in place of the BrainPOP video. The video discusses much of the same material, however, does not specifically mention isotopes and only talks about stability.
If time permits I try to show it twice, so that students can jot down notes for the quiz they will take.
As a wrap-up to this lesson I provide students with the quiz that is provided on the BrainPOP website. It is a short 10 question quiz that can be completed in 5 minutes and handed in before the end of the period. This quiz tends to be a little difficult and only expect an average of 70%, but it does provide enough feedback about what students have taken from the video. I will grade them and hand them back the next period as introduction to the lesson on isotopes.
Most students struggle with the idea that radiation can be useful and that we are exposed to small quantities on a daily basis. The following period I went over the quiz and provide them with a brief explanation of some practical applications for radiation, such as cancer therapy (using iodine-131), PET scans (positron emission), food irradiation, pace makers, power plants and smoke detectors. I told them that as times permits (due to the end of the school year) we would explore as many applications of nuclear radiation as possible.