Day 2: Fission and Fusion Comparison

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Objective

SWBAT compare and contrast nuclear processes (fission, fusion and radioactive decay) in terms of changes in numbers of subatomic particle and characteristics of emitted energy.

Big Idea

Modeling is a great tool for students to learn the difference between fission and fusion...however, no two student models are alike!

Introduction (NGSS alignment)

Performance Expectation

In this lesson students continue to 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.  This standard is illustrated in this lesson with students continuing to explore how energy produced during fission and fusion has practical applications with both pros and cons.

Science and Engineering Practice

This is day 2 of a lesson where students develop a model (as described in NGSS Science Practice 2) illustrating the differences between fission and fusion.  Modeling can take a variety of forms, ranging from a small scale working models of a concept, to a mental models that have students draw, talk about or design personal representations of a concept.  

Crosscutting Concept

This lesson continues to show students that Energy and Matter are part of fission and fusion by having students authentically illustrate their perception of the energy input and output of fission and fusion.

 

Warm-up

7 minutes

Since this activity is a group project, and I want students to finish it using class time, most of the 40 minute shortened period is spent working on the project.  The main goal of this period is to have students complete their projects showing a contrast between fission and fusion, and if time permits, to add extra detail such as color and additional information that was not specified in the rubric.  (The modeling nuclear reactions rubric is further explained later in the lesson).  The hope is that the information from this project will create an authentic understanding that will help them on the test.  See reflection below for more discussion about  testing and Common Unit Assessments.

I typically like to start class with some sort of warm up -- albeit a short one in this case -- that stimulates thinking  related to the day's lesson and allows me to see what prior knowledge they have retained from the previous day’s lesson. 

Today this is a very basic warm-up activity.  Students are with their partners ready to work on their projects, so I randomly pick a group via number (that has been assigned ahead of time) and ask them to mention something they have learned about fission and fusion, the pros and cons of nuclear power, or anything else from the unit beside nuclear decay.

I limit what they can say in this portion of the activity because the objective is for them to build a deeper understanding of the content -- fission and fusion.  Another stipulation that I tell them is that you cannot repeat another person’s comment.  This is why I chose groups randomly; otherwise they fight to go first.  The process of picking a group randomly (via number that is draw from a jar) continues till every group has spoken.

I don’t have video of this portion of the lesson, so here is a short list of student comments:

  1. Fusion has more output than fission.
  2. Nuclear power plant run on U-235
  3. The sun is a of fusion
  4. Fission splits materials
  5. Nuclear power is dangerous.  At this point I had to stop a debate about pros and cons…not that I wanted to…but I had to so they have enough time to finish their projects in class.
  6. Fission splits into two smaller products releasing neutrons.  I really liked this portion of the sharing because it built on another group’s broad comment (# 4) fission and illustrated good listening skills.  I commended them for listening and building on another groups comments

 

Elaborate

35 minutes

After the warm-up I instruct groups that they will have the remainder of the period to complete their projects.  I urge them to work diligently because the projects will be viewed by the entire class tomorrow.  The remainder of the period I keep students focused by walking around and critiquing their poster and asking them about what they drew and why they drew. 

My main goal while critiquing their project is to make sure they have an understanding of the isotopes involved in fission, the amount of energy that is achieved through the processes, a real world example and that fission is the process of larger isotopes being splits into smaller isotopes. 

I have similar requirements of fusion, except that fusion is the combination of smaller isotopes being combined into larger elements and that a larger amount of relatively uncontrollable) energy is achieved.  

Some typically ask questions I ask:

  1. Why can U-235 be split?  And what is it split into? I want them to respond with that it is unstable and the neutron makes it more unstable.  It is split into Kr-92 and Ba-141
  2. What is produced during fusion?  Helium, lots of energy (like the sun) and neutron.

Depending on the project I will ask questions that make them explain why they modeled fission and fusion the way they did.

I particularly use the word model because my students understand that modeling is one of the NGSS Practices used to learn concepts in this unit and will be expected to see the value in modeling.

 

Project Evaluate

Here I show a range of student examples and how and why they received their grade.  I find that this is important for two reason:  (1) it provides students examples that can be used for future reference and (2) it provides insight into how the project can be modified to better suit your instruction.