Lesson plan of Thermodynamics: Internal Energy of a Gas

Objectives (5 - 7 minutes)

1. Understand the Concept of Internal Energy of a Gas: The teacher should help students understand that the Internal Energy of a gas is the sum of all the kinetic and potential energies of the gas particles. This objective is essential for students to be able to understand the other topics of the lesson.

2. Apply the First Law of Thermodynamics to Problems Involving the Internal Energy of a Gas: Students should be able to apply the First Law of Thermodynamics (principle of conservation of energy) to solve problems involving the Internal Energy of a gas. To do this, they must understand that the change in internal energy of a gas is equal to the work done on the gas plus the heat added to the gas.

3. Solve Practical Problems Using the Equation of Internal Energy of a Gas: Students should be able to solve practical problems involving the internal energy of a gas. To do this, they must be able to manipulate the equation of internal energy of a gas, which relates the change in internal energy, the work done on the gas, and the heat added to the gas.

   Secondary objectives:

   • Encourage Group Work and Discussion: The teacher should encourage students to work in groups to solve the proposed problems, promoting discussion and exchange of ideas. This will contribute to the Development of students' communication and collaboration skills.
   • Develop Critical Thinking Skills: The teacher should propose problems that require students to apply concepts from different topics in thermodynamics, thus encouraging the Development of critical thinking skills.

Introduction (10 - 12 minutes)

1. Review of Previous Concepts: The teacher should begin the lesson by reviewing important concepts that were studied previously and that are essential for understanding the topic of the lesson. Among these concepts, the following should be addressed: the definition of thermodynamics, the ideal gas law, the definition of work and heat, and the first law of thermodynamics. This review should be brief and focused on the essential points to save time and maintain students' attention. (3 - 5 minutes)

2. Problem Situations: The teacher should propose two problem situations that arouse the interest of students and that are related to the theme of the lesson. For example:

   • "Imagine that we have a closed container containing a gas. If we heat this container, what happens to the energy of the gas particles? What if we cool the container?"

   • "Suppose we are inflating a balloon. What is the work done by the air that we put inside the balloon? And if we empty the balloon, what happens to the internal energy of the gas?"

   These problem situations aim to arouse students' curiosity and prepare them for the study of the lesson topic. (3 - 4 minutes)

3. Contextualization: The teacher should contextualize the importance of studying the internal energy of a gas, explaining that this is a fundamental concept for understanding natural and technological phenomena, such as the operation of combustion engines and refrigerators. It should also be emphasized that thermodynamics is an area of great relevance to physics, engineering, chemistry, biology, and other sciences. (2 - 3 minutes)

4. Introduction to the Topic: To introduce the topic of the lesson, the teacher can present two curiosities or practical applications of the concept of internal energy of a gas:

   • "Did you know that the internal energy of a gas is responsible for the movement of the particles that compose the gas? That's why when we heat a gas, it expands: the particles gain energy and move with more intensity."

   • "Another interesting example is the operation of balloons. When we fill them with hot air, the internal energy of the air increases and, consequently, its pressure. This causes the balloon to expand and rise. When we empty the balloon, the internal energy of the air decreases and the balloon shrinks."

   These curiosities aim to arouse students' curiosity and show the relevance of the topic to everyday life. (2 - 3 minutes)

Development (20 - 25 minutes)

1. Activity "Balloons in Action" (10 - 12 minutes)

   • Description: In this activity, students will work in groups of 4 to 5 members. Each group will receive an empty balloon, a thermometer, a container with hot water, and another with cold water. The objective is for students to observe and record the changes in the volume of the balloon and the temperature of the water inside it when it is submerged in each of the containers.
   • Step by step: Students should fill the balloon with ambient air and then record the volume of the balloon and the temperature of the water inside it. Next, they submerge the balloon in the container with hot water and observe what happens. After one minute, they record the volume of the balloon and the temperature of the water again. They repeat the procedure with the cold water. Finally, students should discuss in their groups the changes observed, relating them to the concept of internal energy of a gas.
   • Guidelines: The teacher should circulate around the room, assisting groups that encounter difficulties and stimulating discussion. At the end of the activity, each group should present their observations and conclusions to the class.

2. Activity "Thermal Spring" (10 - 12 minutes)

   • Description: In this activity, students will continue working in their groups. Each group will receive a spring, a colored marker, and a hair dryer. The objective is for students to observe and record the changes in the length of the spring and room temperature when heating it with the hair dryer.
   • Step by step: Students should mark the initial length of the spring and the ambient temperature with the marker. Next, they should heat the spring with the hair dryer and observe what happens. After one minute, they should record the length of the spring and the ambient temperature again. They repeat the procedure twice more. Finally, students should discuss in their groups the changes observed, relating them to the concept of internal energy of a gas.
   • Guidelines: The teacher should again circulate around the room, assisting groups that encounter difficulties and stimulating discussion. At the end of the activity, each group should present their observations and conclusions to the class.

3. Group Discussion (5 - 7 minutes)

   • Description: After carrying out the activities, the teacher should promote a group discussion. Each group will have up to 3 minutes to present their observations and conclusions. Next, the teacher should synthesize the presentations, highlighting the most relevant points and relating them to the theory.
   • Guidelines: During the discussion, the teacher should encourage the participation of all students, ask questions that stimulate critical thinking, and correct any errors in interpretation. The objective is for students to be able to relate the practical activities to the concept of internal energy of a gas and the first law of thermodynamics.

Return (8 - 10 minutes)

1. Group Discussion (3 - 5 minutes)

   • Description: The teacher should promote a group discussion after the Conclusion of the practical activities. Each group will have up to 3 minutes to present their observations and conclusions. Next, the teacher should synthesize the presentations, highlighting the most relevant points and relating them to the theory.
   • Guidelines: During the discussion, the teacher should encourage the participation of all students, ask questions that stimulate critical thinking, and correct any errors in interpretation. The objective is for students to be able to relate the practical activities to the concept of internal energy of a gas and the first law of thermodynamics.

2. Connection with Theory (2 - 3 minutes)

   • Description: After the discussion, the teacher should explain how the practical activities relate to the theory. It should be highlighted how the changes observed (in the volume of the balloon and the temperature of the water, and in the length of the spring and the ambient temperature) are related to the concept of internal energy of a gas and the first law of thermodynamics.
   • Guidelines: The teacher should make a brief review of the theoretical concepts, highlighting the main ideas and relating them to the observations made by the students. It should be emphasized that thermodynamics is an experimental science, and that practical activities are a way to confirm and deepen the understanding of theoretical concepts.

3. Individual Reflection (2 - 3 minutes)

   • Description: To end the lesson, the teacher should propose that students do an individual reflection on what they have learned. The teacher should ask questions such as: "What was the most important concept you learned today?" and "What questions have not yet been answered?" Students should write down their answers on a piece of paper, which will be collected by the teacher at the end of the lesson.
   • Guidelines: The teacher should explain that this reflection is a way to assess what students have learned and identify possible difficulties or gaps in understanding. It should be emphasized that all answers are valid, and that the objective is not to find the "right" answer, but rather to promote reflection and self-knowledge.

4. Feedback (1 minute)

   • Description: The teacher should end the lesson by giving feedback to the students on their performance during the lesson. He/she should praise the participation, collaboration, and effort of the students, and emphasize the importance of continuous study and practice for learning physics and thermodynamics.
   • Guidelines: The teacher should encourage students to continue studying and practicing the concepts learned, and to ask their doubts in the next classes. Students should also be reminded about the importance of reviewing the content at home, and of doing the exercises proposed in the textbook.

Conclusion (5 - 7 minutes)

1. Lesson Summary (2 - 3 minutes)

   • Description: The teacher should begin the Conclusion of the lesson by summarizing the main points covered, reinforcing the definition of internal energy of a gas, the application of the first law of thermodynamics, and the solution of practical problems using the equation of internal energy of a gas.
   • Guidelines: The teacher should use clear and accessible language, avoiding the excessive use of technical terms. The most important concepts and the relationships between them should be emphasized, not just repeating what was said during the lesson.

2. Connection between Theory, Practice, and Applications (1 - 2 minutes)

   • Description: Next, the teacher should explain how the lesson connected theory, practice, and applications. It should be highlighted how the practical activities allowed students to observe and better understand the theoretical concepts, and how these concepts are applied in everyday situations and in technologies such as combustion engines and refrigerators.
   • Guidelines: The teacher should emphasize that physics is an experimental science, and that practice is an essential part of the learning process. Students should also be reminded that understanding theory is essential for solving problems and applying concepts in practical and real situations.

3. Extra Materials (1 minute)

   • Description: The teacher should suggest some extra materials for students who wish to deepen their understanding of the topic of the lesson. These materials may include educational videos, simulation websites, and virtual experiments, reference books and articles, among others.
   • Guidelines: The teacher should briefly explain the content of each material and how they can help students consolidate what was learned in class. It should also be emphasized that the use of these materials is optional, and that the most important thing is for students to practice what they have learned and ask their doubts in the next classes.

4. Importance of the Subject (1 minute)

   • Description: Finally, the teacher should summarize the importance of the subject for students' daily lives and for society as a whole. It should be highlighted that the study of thermodynamics and the internal energy of a gas is essential for understanding natural and technological phenomena, and for the Development of many technologies and practical applications.
   • Guidelines: The teacher should encourage students to reflect on the importance of physics and thermodynamics in their lives, and to realize that what they are learning is not just a set of formulas and abstract concepts, but rather a powerful tool for understanding and transforming the world around them.