Objectives (5 - 10 minutes)

1. Understanding the Fundamental Concepts:

   • Students should be able to define and differentiate the different states of matter: solid, liquid, and gas.
   • They should understand that state changes occur when there is a change in the energy of a substance.

2. Identifying State Changes:

   • Students should be able to identify everyday situations where state changes of matter occur and to explain the chemical phenomenon behind such changes.

3. Applying the Concepts:

   • Students should be able to apply the concepts of state changes to problem situations, such as the transformation of ice into water or the boiling of water.

Secondary Objectives:

• Developing Critical Thinking:

  • Students should be encouraged to think critically about state changes, questioning why they occur and how they affect the world around them.

• Encouraging Active Participation:

  • The teacher should promote active student participation throughout the class, encouraging questions, discussions, and the presentation of practical examples.

Introduction (10 - 15 minutes)

1. Review of Previous Concepts:

   • The teacher should begin the class by recalling the concepts of pure substances and mixtures as well as the different physical states of matter (solid, liquid, and gas). This review helps set the stage for the new topic of state changes.

2. Problem Situation 1: "The Disappearing Ice Cube":

   • The teacher might describe a situation in which an ice cube disappears in a glass of water without anyone touching it. This situation can spark student curiosity and encourage them to think about what could have happened.

3. Problem Situation 2: "Mysterious Vapor":

   • Another situation that can be presented is the appearance of vapor in a pot of boiling water. Students can be challenged to explain where the vapor comes from and why it only forms at a certain temperature.

4. Contextualization: Importance of State Changes:

   • The teacher should then contextualize the importance of state changes, explaining that these phenomena are present in many aspects of our daily life, such as cooking, meteorology, energy production, among others. This helps pique student interest by showing the relevance of the topic.

5. Introducing the Topic: "Understanding State Changes":

   • The teacher then formally introduces the topic of the class: State Changes. The teacher might explain that throughout the class, students will learn about the different state changes (melting, solidification, vaporization, condensation, and sublimation) and how they occur.

6. Curiosities: "Why is Ice Slippery?" and "What is Dry Ice Sublimation?":

   • To further engage students' interest, the teacher could share two curiosities: the first one is about why ice is slippery even though it is a solid; and the second one is about the sublimation of dry ice, which goes directly from the solid to the gas state, without going through the liquid state.

This Introduction will allow students to engage with the topic and build a solid foundation for the learning of the rest of the class.

Development (20 - 25 minutes)

1. Theory: Basic Concepts of State Changes (5 - 7 minutes):

   • The teacher should start the theoretical part by explaining that state changes are physical phenomena that happen when a substance's energy changes and focus on the kinetic energy of the particles.
   • The teacher should explain that in a solid state, particles are very close to each other and have little kinetic energy; in a liquid state, particles are further apart and have more kinetic energy; and in a gas state, particles are very far apart and have high kinetic energy.
   • The teacher should introduce the terms "melting" (passing from solid to liquid), "solidification" (passing from liquid to solid), "vaporization" (passing from liquid to gas), "condensation" (passing from gas to liquid) and "sublimation" (passing from solid to gas without going through the liquid).
   • The teacher should emphasize that these state changes happen due to changes in the kinetic energy of the particles and can be either reversible or irreversible.

2. Application: Practical Examples of State Changes (5 - 7 minutes):

   • The teacher should then present practical examples of state changes, revisiting the problem situations presented in the Introduction and explaining them in the light of the theory.
   • The teacher might also bring other examples, such as the evaporation of water from a puddle on a hot day, the formation of frost in a fridge, or the sublimation of dry ice.
   • The teacher should ask students to describe what is happening in each example, reinforcing the practical application of the theoretical concepts.

3. Discussion: State Changes and Our Daily Life (5 - 7 minutes):

   • The teacher should then open for a discussion about how state changes are present in our daily life.
   • The teacher might ask students whether they can think of more examples of state changes, and how they affect the world around us.
   • The teacher should encourage students to think critically, questioning why state changes are important and how they can be used in different contexts (e.g., cooking, meteorology, energy production, etc.).
   • The teacher should also highlight the importance of understanding state changes for the comprehension of other chemical and physical phenomena.

4. Practical Activity: Experiment with State Changes (5 - 7 minutes):

   • The teacher should, if possible, perform an experiment in the classroom to demonstrate a state change.
   • One example can be the demonstration of dry ice sublimation. The teacher could briefly explain what dry ice is (carbon dioxide in solid state) and then show how it goes directly into the gas state, without passing through the liquid state, when it is exposed to room temperature.
   • During the experiment, the teacher should explain step by step what is happening, reinforcing the concepts of state changes and kinetic energy of the particles.
   • At the end of the experiment, the teacher should review the concepts learned and answer any questions students might have.

This Development stage will allow students to grasp the theoretical concepts, see how they are applied in practice, and reflect on the importance of state changes in our daily life.

Feedback (10 - 15 minutes)

1. Group Discussion (3 - 5 minutes):

   • The teacher should divide the class into small groups and ask them to discuss amongst themselves about what was learned in the class.
   • They should share their perceptions on the state changes, the practical examples presented and how such phenomena are present in our daily life.
   • The teacher should circulate in the room, listening to the discussions and clarifying questions that may arise.

2. Connection with Theory (3 - 5 minutes):

   • After the group discussion, the teacher should gather the class and promote a reflective activity together.
   • The teacher might ask students how they relate their discussions with the theory presented in the class.
   • The teacher should encourage students to justify their answers, stimulating critical thinking and articulation of ideas.

3. Verification of Learning (3 - 5 minutes):

   • The teacher should then propose a learning verification activity.
   • The teacher might ask oral or written questions about the state change concepts, or ask students to explain, in their own words, what they understood about the matter.
   • The teacher should evaluate students' answers, clarifying possible misconceptions and reinforcing the concepts that were not understood yet.

4. Final Reflection (1 - 2 minutes):

   • To wrap up the class, the teacher should propose that students reflect, for a minute, on what they learned.
   • The teacher could ask questions such as, "What was the most important concept learned today?", "What questions were not answered yet?" and "How can you apply what you learned to your own life?".
   • The teacher should encourage students to share their reflections, if they feel comfortable.

5. Homework:

   • Finally, the teacher should propose homework that reinforces the concepts learned.
   • This might include solving problems involving state changes, researching more examples of state changes in the daily life or writing a report about the experiment done in class.

This Feedback stage will allow the teacher to assess the effectiveness of the class, clarify questions, reinforce the concepts learned and stimulate students' reflection on what was learned.

Conclusion (5 - 10 minutes)

1. Summary (2 - 3 minutes):

   • The teacher should start the Conclusion by recalling the main points addressed during the class.
   • The teacher should stress the definition of state changes, the different states of matter, the change in kinetic energy of the particles during state changes and the different types of state changes.
   • The teacher might do this in an interactive way, such as asking students to complement the teacher's explanation based on what they have learned.

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

   • The teacher should then emphasize how the class connected theory (the concepts of state changes) with practice (the examples of state changes presented and the experiment conducted).
   • The teacher could highlight how the understanding of the theoretical concepts enabled students to understand the practical phenomena observed.

3. Complementary Materials (1 - 2 minutes):

   • The teacher should then suggest extra materials for students who want to deepen their knowledge about the topic.
   • This might include additional readings, explanatory videos, interactive websites or practical activities that students can do at home.
   • The teacher should stress that the autonomous exploration of such complementary materials is an excellent way to reinforce learning and clarify possible doubts.

4. Importance of the Topic (1 - 2 minutes):

   • Finally, the teacher should wrap up by summarizing the importance of state changes, reinforcing that such phenomena are present in our daily life and that their understanding is essential for the comprehension of many other chemical and physical phenomena.
   • The teacher might provide examples of how state changes are used in different contexts, such as cooking, meteorology, energy production, among others.
   • The teacher should encourage students to observe and question state changes in their day-by-day, reinforcing the applicability of the concepts learned.

This Conclusion will allow students to consolidate the knowledge acquired, grasp the relevance of the topic and feel encouraged to keep learning about it.