Objectives (5 - 7 minutes)

1. Understand the life cycle of stars: The teacher must ensure that students understand the sequence of events that occur during the life cycle of a star, from its formation to its death. Students should be able to identify and explain each of the stages, including the formation of nebulae, nuclear fusion, the formation of heavier elements, and the different forms of stellar death.

2. Differentiate between types of stars: Students should be able to distinguish between different types of stars based on their characteristics, such as size, temperature, brightness, and color. This includes identifying dwarf stars, giants, supergiants, and white dwarfs. In addition, students should be able to explain how these different types of stars form and evolve over time.

3. Relate the life cycle of stars to the evolution of the universe: Finally, students should be able to relate the life cycle of stars to the overall evolution of the universe. This includes understanding how the formation and death of stars contribute to the creation of new elements, the expansion of the universe, and the formation of structures such as galaxies and star clusters.

   Secondary objectives:

   • Promote research and autonomous study skills: Through the inverted classroom methodology, students will be encouraged to seek information on the topic before class, preparing for discussions in the classroom and deepening their understanding of the subject.

   • Develop critical thinking and problem-solving skills: Students should be encouraged to analyze and discuss the different stages of the life cycle of stars, thinking critically about the physical processes involved and how they contribute to the evolution of the universe. In addition, students will be challenged to solve practical problems related to the topic, such as determining the age of a star based on its observable characteristics.

Introduction (10 - 15 minutes)

1. Review of previous content: The teacher should start the lesson by reviewing previously learned concepts that are fundamental to understanding the current topic. This includes the definition of a star, the basic structure of a star (core, fusion zone, radiative zone, convective zone, photosphere, chromosphere, and corona), the importance of nuclear fusion inside stars, and the brightness and stellar temperature scale. This review can be done through a brief classroom discussion or a quick quiz.

2. Problem situations: The teacher can propose two problem situations to arouse students' interest and contextualize the topic. The first one could be: "Why does the Sun shine? And what will happen to it in the future?" The second one could be: "How can astronomers determine the age of a star that is millions of light-years away?" The teacher should encourage students to think about these questions and make assumptions based on what they already know.

3. Contextualization: The teacher should then explain the importance of studying stellar evolution, highlighting how this process is fundamental for the formation of chemical elements, including those that make up our own bodies. In addition, the teacher can mention how the death of a star can lead to the formation of new stars and complex structures, such as galaxies. To illustrate these points, the teacher can share some curiosities, such as the fact that every oxygen atom we breathe was produced inside a star that has already died.

4. Introduction to the topic: Finally, the teacher should introduce the topic of the lesson - stellar evolution. The teacher can start by sharing some curiosities about the life cycle of stars, such as the fact that stars can vary in size from a small red dwarf, which has only 0.1% of the Sun's mass, to supergiants like Betelgeuse, which is over 700 times larger than our Sun. Another interesting curiosity is that eventually, all stars, including the Sun, will die. The teacher should then explain that the goal of the lesson is to better understand these processes of birth, life, and death of stars.

Development (20 - 25 minutes)

1. Activity "Creation of a Stellar Life Cycle" (10 - 12 minutes): In this activity, students will be divided into groups of up to five people. Each group will receive a set of cards, each representing a stage of the life cycle of a star (for example, formation of nebulae, nuclear fusion, formation of heavier elements, stellar death). The goal is for students to put the cards in order, creating a stellar life cycle.

   • Step 1: The teacher should provide each group with a set of cards. Each card should have a stage of the life cycle of stars written on it, along with a brief description of what happens at that stage.

   • Step 2: The students in each group should discuss the stages and put the cards in order. They should also try to relate each stage to the energy released, the formation of new elements, and the changes in the star's structure.

   • Step 3: Once the groups have put the cards in order, they should present their stellar life cycle to the class. While the groups present, the teacher should guide a discussion about the similarities and differences between the stellar life cycles created by the different groups.

2. Activity "Stars in Motion" (10 - 12 minutes): In this activity, students will simulate the movement of different types of stars in space.

   • Step 1: The teacher should provide each group with a lamp of different colors and sizes, representing different types of stars. The teacher should also provide a black sheet of paper and some pins.

   • Step 2: The students in each group should pin the lamp to the black sheet of paper using pins. They should then turn on the lamp and observe how the light spreads on the paper, creating an illuminated area (representing the fusion zone and the photosphere) and a less illuminated area around it (representing the corona).

   • Step 3: The students should then move the lamp in different directions and observe how the illuminated area changes in shape and size. They should then discuss how this movement can be used to determine the rotation of a star.

   • Step 4: Finally, the students should vary the distance between the lamp and the paper and observe how it affects the size of the illuminated area. They should then discuss how this observation can be used to determine the distance of a star from Earth.

3. Activity "The Death of a Star" (5 - 6 minutes): In this quick activity, students will simulate the death of a high-mass star, forming a supernova.

   • Step 1: The teacher should provide each group with a balloon and some confetti in different colors, representing the heavier elements formed during the death of a star.

   • Step 2: The students in each group should inflate the balloon with air (representing nuclear fusion in the star's core) and then burst it (representing the supernova). They should observe how the confetti (representing the heavier elements) spreads.

   • Step 3: The students should then discuss how this activity represents the death of a high-mass star and the formation of new elements during a supernova.

   • Step 4: The teacher should emphasize that, although the activity was fun, supernovas are extremely violent and destructive events in the real universe.

Return (8 - 10 minutes)

1. Group Discussion (3 - 4 minutes): The teacher should promote a group discussion moment, where each team shares their solutions or conclusions from the activities carried out. This is a crucial moment for the consolidation of the concepts presented in the lesson. During the discussion, the teacher should ensure that each group has the opportunity to present their findings and that students are encouraged to ask questions and make comments. The teacher can guide the discussion by asking questions that lead students to think more deeply about what they have learned. For example, "How did the 'Stars in Motion' activity help us better understand stellar evolution?" or "What did we learn from the 'Death of a Star' activity about the formation of new elements in the universe?".

2. Connection to Theory (2 - 3 minutes): After the group discussion, the teacher should summarize the main points raised by the students and make the connection to the theory presented at the beginning of the lesson. The teacher should clarify any misunderstandings and ensure that all students have understood the fundamental concepts. To do this, the teacher can use practical examples, analogies, and images to reinforce students' understanding.

3. Final Reflection (2 - 3 minutes): To close the lesson, the teacher should propose that students reflect for a minute on the following questions:

   1. What was the most important concept learned today?
   2. What questions have not been answered yet?

   After the reflection time, the teacher should ask some students to share their answers with the class. This is an opportunity for the teacher to assess students' understanding and identify possible gaps in learning. In addition, students' answers can provide valuable insights for planning future lessons.

4. Teacher Feedback (1 minute): Finally, the teacher should provide overall feedback to the class, praising everyone's effort and participation and reinforcing the key learning points. The teacher should also encourage students to continue exploring the topic on their own, suggesting additional study materials such as videos, books, and astronomy websites.

This Return moment is essential to consolidate students' learning, validate their discoveries and reflections, and encourage them to continue exploring the topic outside the classroom.

Conclusion (5 - 7 minutes)

1. Summary of Contents (2 - 3 minutes): The teacher should start the Conclusion by summarizing the main points covered during the lesson. This includes the definition and characteristics of the life cycle of stars, the differentiation between different types of stars, and how stars form and evolve over time. The teacher can use diagrams or visual schemes to reinforce these concepts clearly and concisely. In addition, the teacher should recall the practical activities carried out and how they helped illustrate and deepen the understanding of these concepts.

2. Theory-Practice-Applications Connection (1 - 2 minutes): The teacher should then explain how the lesson connected theory, practice, and applications. This can be done by highlighting how the theory of the life cycle of stars was applied in practical activities, and how these activities helped illustrate real and applicable situations. The teacher can also mention how understanding the life cycle of stars has practical applications in astronomy and in understanding the universe.

3. Extra Materials (1 - 2 minutes): The teacher should suggest additional study materials for students who wish to delve deeper into the topic. This may include books, documentaries, astronomy websites, and simulation apps. The teacher can emphasize the importance of continuing to study the subject, not only to improve academic performance, but also to develop curiosity and critical thinking.

4. Relevance of the Subject (1 minute): Finally, the teacher should reinforce the importance of the subject presented for students' daily lives. The teacher can explain how understanding the life cycle of stars helps to understand the origin of chemical elements, the formation of galaxies, and the evolution of the universe. In addition, the teacher can mention how astronomy, in general, contributes to our appreciation of the world around us and to the development of technologies and innovations.