Fusion Reactions: How and Where are Elements Created?

NASA - Goddard Space Flight Center
Type Category
Instructional Materials
Informative Text , Instructor Guide/Manual , Activity
This resource, vetted by NSTA curators, is provided to teachers along with suggested modifications to make it more in line with the vision of the NGSS. While not considered to be "fully aligned," the resources and expert recommendations provide teachers with concrete examples and expert guidance using the EQuIP rubric to adapted existing resources. Read more here.



Part 1 of the X-ray Spectroscopy Unit from NASA’s Imagine the Universe! lesson plans includes a series of three lessons on the formation of elements in stars. During this three lesson series, students learn about the life cycle of stars and model the formation of elements in stars. The lessons are a demonstration of type so fusion reactions and modeling not just the changes to matter during the processes but also the energy involved in these reactions.

Intended Audience

Educator and learner
Educational Level
  • Grade 12
  • Grade 11
  • Grade 10
  • Grade 9
  • High School
Access Restrictions

Free access - The right to view and/or download material without financial, registration, or excessive advertising barriers.

Performance Expectations

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.

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.

This resource is explicitly designed to build towards this performance expectation.

Comments about Including the Performance Expectation
The first two parts of this three-part series of lessons includes background knowledge students need in order to be able to model the changes in atomic nuclei in stars. Background information is provided in text format for students on the life cycle of stars and formation of elements in stars. In the third lesson, students work collaboratively to develop models for fusion reactions, demonstrating changes in the nuclei of atoms and energy changes in the reactions. The model students develop in this activity does not require clear indication from students that they can identify changes in the quantities and ratios of subatomic particles that make up the nuclei represented in the processes they are representing. It is important for the teacher to consider questions to probe students’ understanding of these changes during the activity to emphasize how successive nuclei are changing from the parent nuclei and how that is represented through the symbols used to represent the changes. Posing questions to students while they develop their models will be beneficial in facilitating the later learning activities as the teacher will anticipate needed support for students. It is expected for students to include energy in the models while they are using index cards to demonstrate the nuclear processes. However, there is no expectation for students to consider the scale of energy released during the reactions. A follow up to the lesson or addition in this lesson series is needed in order to address this component of the fusion reactions.

Science and Engineering Practices

This resource is explicitly designed to build towards this science and engineering practice.

Comments about Including the Science and Engineering Practice
Through these lessons, students use written description of nuclear fusion reactions to create first a diagram and then a model of the nuclear equations to represent the changes to nuclei in the formation of elements in stars. Students must interpret information described in the background information on the life cycle of stars to first create a diagram documenting the life cycle of a high-mass star (Lesson 1). Then, in the Fusion Reactions Activity (Lesson 3) students use prior knowledge of subatomic particles and isotopes with what they have learned about the formation of elements in stars to develop models of the nuclear fusion reactions that occur in stars, creating gradually heavier nuclei. To further emphasize the use of these multiple representations and consider the merits and limitations of each, students should be asked to compare the representations of the processes in an assessment following the lessons. Students could be asked to compare the level of detail included in each representation and the benefits of the format of the representations. A strong extension for this lesson would be to ask students to create a pictorial representations of one fusion reaction, showing the subatomic particles that make up the nuclei represented and have them reflect on this model compared to the other representations examined in the lessons, with particular focus on reactions that lead to the formation of iron for clear comparisons.

Disciplinary Core Ideas

This resource appears to be designed to build towards this disciplinary core idea, though the resource developer has not explicitly stated so.

Comments about Including the Disciplinary Core Idea
In developing the models of the nuclear fusion reactions in stars, students must consider what it means to have these equations “balance.” To further emphasize this concept for students, they should be asked to explain the choices for products of the reactions and the evidence of energy in these processes. Students will need to refer back to the background information and prior knowledge of the makeup of nuclei to be able to accurately explain the models. The teacher should emphasize using textual evidence as well as prior learning in their explanations.

Crosscutting Concepts

This resource was not designed to build towards this crosscutting concept, but can be used to build towards it using the suggestions provided below.

Comments about Including the Crosscutting Concept
An implicit focus of these lessons is to construct explanations for how elements are formed during nuclear fusion processes in stars. While the models are intended to be explanatory of these processes, it is left to the teacher to emphasize the value of the models for explanatory purposes. Teachers can emphasize this by posing questions to students while they are modeling the nuclear processes during the Fusion Reactions Activity.

Resource Quality

  • Alignment to the Dimensions of the NGSS: The lessons in this series provide a valuable context for students learning about fusion reactions in alignment with the three dimensions of the NGSS. However, the activities stop short of emphasizing the explanatory nature of the models students create of the processes in a way that would allow for using Science Practices to make sense of the phenomenon. Adding opportunities for students to create pictorial representations of the processes, as suggested above, would be a good way to strengthen the lessons.

  • Instructional Supports: Further support is needed to allow all students to access the information from the background readings, including English language learners and students reading well below grade level. The information in these readings is critical for students to be successful in the modeling activity so it is essential for teachers to provide appropriate scaffolds or modified versions of the readings. The scaffolds provided may include graphic organizers or other tools that help students organize the information in a way that can be referenced in the later activities. This support is critical for student success in developing models for the nuclear reactions as outlined in this lesson.

  • Monitoring Student Progress: There are opportunities with each of the three lessons to monitor student progress using formative assessment strategies. In particular, the first diagram students create representing the life cycle of a star from the reading in Lesson 1 is a good opportunity for teachers to check student understanding of the formation of elements through nuclear fusion in stars. Then, in Lesson 3, there is opportunity for ongoing feedback through questioning as students develop models for the nuclear reactions creating successively heavier elements. Additional consideration should be given to how to make best use of the reading in Lesson 2 towards the overall learning goal for the lessons.

  • Quality of Technological Interactivity: - none -