Formative Assessment in Nuclear Chemistry

The standard is as follows: 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.] (HS-PS1-8)

The standard wants students to be able to illustrate various nuclear reactions qualitatively and to understand how to model changes during these reactions.

Big ideas for overall unit: Conservation of mass and energy. Protons/neutrons stay the same during nuclear reactions.

The particular learning performance objective I chose: Students identify alpha, beta and gamma decay products.

Since the standard emphasizes that this is a qualitative type of standard, I do not expect students to be able to fully use alpha, beta or gamma decay in nuclear reaction equations. Instead, I expect them to differentiate between the types of decay products and to compare and contrast them. Two important facets come from this expectation. First, I want students to understand how these different products act differently. This means I will introduce them to the idea of penetration depth, how far the decay products can penetrate. They will learn that alpha particles are stopped by a sheet of paper or even their own skin. They will learn that gamma rays are highly penetrating, needing thick slabs of lead to stop them. Secondly, students will learn several common nuclear reactions that create these products so they have a context for these particles in the “real” world.

As I teach to this learning objective I will make use of many formative assessment techniques. In general formative assessments should give the students descriptive feedback, identify their current comfort level with the topic, and give a pathway toward achieving full proficiency. Each of my formative assessments will not only let me know how well my students understand alpha, beta and gamma decay particles, but also give them a self-check and an understanding of what they need to do to achieve higher proficiency.

The first formative assessment I will use is a “Yes/No” chart that will be used both individually and in a group. Often a student thinks he or she is the only one with a specific question, so the use of this chart will help students understand that their peers are having similar difficulties and give me the opportunity to provide descriptive feedback to the class as a whole. Students will be asked to list what they do and don’t understand about a given topic, Yes or do know on the left and No or don’t know on the right. They will do this work individually during a Do Now time at the beginning of class. Once they have completed a list with a minimum of three items in either column we will have a class discussion where we put a universal Yes/No chart on the whiteboard up front. This will serve the purpose of answering specific questions students have while also showing them that their peers are facing similar difficulties.

The next formative assessment will focus on how students see alpha, beta and gamma particles in the greater context of nuclear chemistry/physics. Students will be asked to diagram the context of these particles, e.g. draw out or explain how alpha, beta and gamma particles relate to nuclear reactions. Once again they are not expected to have any quantitative mastery of the subject, but rather be able to place these particles in the greater pictures of isotopes and nuclear chemistry. For example, students could explain how all of these particles result from nuclear decay, which in turn might happen in carbon atoms used in carbon dating. This can be done visually or verbally. Upon completion this assignment will be turned into the bin and used to inform future lessons.

The next assessment is very similar to the last in that it focuses on illustration, which is good because modeling and illustration is a focus of the standard. Students will be asked to sketch out what they do understand about alpha beta and gamma particles. There is no expectation of a broader context in this case, rather just a check to see what students know. Evaluation of this visualization will give students direct feedback about concepts that are unclear to them in addition to giving them positive feedback for the aspects of their visualizations that are correct. Specifically. Students will be asked to draw alpha, beta and gamma particles and illustrate some of their differences visually. This will be done individually followed by a group activity where students sketch on small whiteboards together. Each group will share their whiteboard with the entire class, allowing for feedback from both the teacher and their peers.

The next type of formative assessment is less specific. Comprehension checks at the end of class are important and a variety of questions can be asked on an exit ticket. That said, the questions asked during the alpha, beta and gamma particles portion of the unit will focus on the students’ ability to illustrate these particles and place them in a broader context. These tickets will be collected after every class period and used as a medium to give detailed feedback and suggest strategies for improving comprehension. This is a more direct link between teacher and student than some of the other strategies that are more generalized to the group.

Another more general strategy I will use as a formative assessment in the classroom is notebook checking. Students are expected to keep an up to date notebook that includes handouts, quizzes, and tests as well as their notes from class. Randomly after a class I will ask students to turn in their notebooks for a comprehension/completion check. This random chance assessment promotes good note taking and attentiveness in class, but also gives me the chance to evaluate their comprehension of the subject. In this context as well as in the context of the exit ticket I can give directed feedback that will help the student study better and rise to proficiency. This formative assessment will be used in all my classes, regardless of which unit we are in, because it helps keep both the teacher and the students accountable.

Each of these formative assessments will help me understand how well my students comprehend what alpha, beta and gamma particles are and how well they understand how these particles fit into the greater context of isotopes and nuclear reactions. I don’t want my students to be simply memorizing information; I want them to be creating a new understanding of the world around them. These in depth formative assessments will help make that possible.

Reflection on Understanding and Applying Standards

The process of going from standard to lesson plan is a complicated one that we have just begun to unravel. Unpacking a standard can be extremely difficult considering standards are often dense with additional implications that may not be directly addressed in the wording. For example, the standard I chose to focus on for nuclear chemistry mentioned mass and energy conservation, protons and neutrons, and even alpha, beta and gamma decay processes, but it never mentioned isotopes. Since isotopes are the foundation of understanding that different atomic elements can be heavier or lighter but still have the same charge and chemical characteristics, addressing isotopes in the learning objectives is essential. Thus, to fully unpack the standard, I needed to dig deeper and use my own knowledge of nuclear chemistry to fully understand what knowledge the standard required.

I find that backward mapping is not a particularly new concept to me despite the fact that I haven’t been formally taught it before. Every day when I go to the ice rink and coach my private and group lesson students, I’m practicing backward mapping. I know the element they need to perform, say an Axel jump, and I go backward from there to look at the skills required to get to that point. It makes perfect sense that this process works just as well in classroom teaching. After all, looking at the end product required, determining the assessments needed and the activities to be accomplished does a very good job of setting up how lessons will be shaped. The nuclear chemistry standard I chose had several very clear proficiencies it required, which led to productive backward mapping from these proficiencies. For example, students need to be able to explain the conservation of neutrons and protons in nuclear reactions. This means they need to understand isotopic formalism and to identify decay products of nuclear reactions. Each of these becomes a proficiency required for the standard from which assessments and learning objectives can be created.

Once the backward mapping and unpacking of the standard has been completed, writing learning objectives is fairly straightforward. All that is left is identifying the specific skills required by the proficiencies and turning them into learning objectives with specific verbs. For example, in my nuclear chemistry objectives I use “explain,” “identify” and “give examples” in my wording. These verbs can be assessed in traditional written test formats, during oral presentations and in written assignments such as research reports. I believe it is very important to put these objectives in the voice of the student. An objective must be something the student can say, such as “I can identify alpha, beta and gamma decay products.”

The processes of unpacking, backward mapping and writing learning objectives do a great deal to simplify the translation of a standard into a lesson plan. These tools make it clear what students are expected to do and how these tasks meet the expectations of the standard. The backward mapping is essential for creating useful and pertinent lesson planning. Remembering what standards we want students to meet and creating lesson plans tailored to the skills explicitly or implicitly included in those standards will make a big difference in the classroom. Each lesson I teach my skating students is directed toward them gaining a skill; teaching in the classroom should be no different.

I find that unpacking science standards can be difficult, especially if a teacher doesn’t have a super strong science background. I’ve been around the science block, taking classes in physics, astronomy, geology, and geochemistry, so I’m able to dig deeper into the meaning of certain science standards. I worry, however, that I might be missing something if the standard is not in my area of expertise. Making the unpacking, backward mapping and learning objective process a collective one can solve this problem. At the school where I am student teaching, the chemistry department does an exceptional job of working together to unpack standards, define the “big ideas,” backwards map each of the units, and work together to create achievable learning objectives. I feel this process would be best done in a collective environment like that and that in doing these activities in isolation we only touched the tip of the iceberg.

Backward Design Example

To begin thinking about lesson planning, I’ve chosen a standard from the Next Generation Science Standards that could be applied in a physics or chemistry classroom. Nuclear reactions are at the core of both atomic physics and nuclear chemistry so I believe this standard is important for use in both high school physics and chemistry. The lesson plan that I have devised is for a non-AP level course in either physics or chemistry. At the AP level students would be required to balance nuclear equations, but that is beyond the scope of the standard I have chosen.

The standard is as follows: 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.] (HS-PS1-8)

The standard wants students to be able to illustrate various nuclear reactions qualitatively and to understand how to model changes during these reactions.

The big idea of this standard is that mass and energy interchange during nuclear reactions, but conservation of mass and energy still applies. This is specifically seen in understanding that in nuclear reactions atoms are not conserved, but the total number of protons plus neutrons is conserved.

To identify my learning plan for this unit, I first identified a number of proficiencies I wanted my students to achieve during the unit:

1.     Students illustrate that the total number of neutrons and protons are conserved in nuclear reactions.

2.     Students describe how the total amount of energy and matter in a system is conserved.

3.     Students illustrate the flow of matter and energy in and out of a nuclear reaction

4.     Students identify alpha, beta and gamma decays

5.     Students discuss different nuclear reactions in an informed manner with their peers and the teacher.

6.    Students can visualize different isotopes and show different numbers of neutrons in their visualizations.

To further identify what I want my students to be able to achieve during this unit I devised the following assessments:

1.     Final assessment where students are able to perform proficiently on written assessment that asks:

a.     Free response questions about alpha, beta and gamma decays

b.     Asks them to illustrate fission and fusion reactions

c.      Gives several multiple choice questions about the nature of matter and energy in nuclear reactions

2.     Final student presentation

a.     A short ~5 minute presentation to the class where they describe a nuclear reaction of choice.

b.     Show proficiency in illustrating nuclear reactions

c.      Show proficiency while discussing nuclear reactions

d.     Identify what type of decay is happening in their reaction

3.     Formative assessment using several quizzes are given throughout the unit:

a.     Quiz on the differences between fission, fusion and other decay processes

b.     Quiz on identifying nuclear reaction species: alpha, beta, gamma

c.      Quiz on neutron and proton roles in nuclear reaction and the conservation of mass and energy

4.     Research project on a nuclear processes

a.     Students identify a nuclear reaction that interests them

b.     Students write a 1-2 page report on the history/discovery of the reaction and its applications in the “real” world

To guide my students toward success in these assessments and proficiencies, I constructed a few learning activities that would help solidify the nuclear reaction concepts for my students:

1.     Group activity to understand alpha, beta and gamma decays

a.     Given in a group-quiz style

b.     Groups are asked to identify if the decay products are alpha, beta or gamma decays. No balancing of the equations will be needed.

2.     Workshop to learn how to illustrate fission vs. fusion

a.     Students work in groups and then independently

b.     In the style of “I do, we do, you do together, you do”

c.      By the end of the exercise, students are comfortable with the differences between fission and fusion

3.     Whiteboard session on fission, fusion and other decay processes

a.     Groups of students are given a fusion, fission or basic nuclear decay reaction on a note cards

b.     Students illustrate on a white board each of their reactions and then present to the class. Each groups is given a different reaction.

c.      When sharing the whiteboards to the entire class, the students are asked to identify familiar and different aspects of their reaction illustrations.

Finally, after specifying learning proficiencies, designing assessments and constructing activities, I have a good idea of how I want to structure my unit. I realize there are several lessons on foundational material that will have to occur first. This includes having students understand what an isotope is and what conservation of mass and energy really looks like. I also believe in putting science into an understandable historical context, so I will have an entire lesson addressing nuclear chemistry and its context in the making of the atomic bomb.

The learning units I propose after initial study are:

1.     Isotopes

2.     Conservation of mass and energy

3.     Fission vs. Fusion

4.     Alpha and Beta particles

5.     Gamma radiation

6.     Nuclear reactions and equations

7.     Historical context of nuclear chemistry: The Atom Bomb

I’m sure this unit will continue to evolve, but the analysis of proficiencies, assessments and learning activities gives me a good foundation.