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.