Objectives (5-7 minutes)

1. Understand the composition of air: Students should be able to understand that air is composed primarily of nitrogen, oxygen, and small amounts of other gases. They should also learn about the importance of these components in sustaining life on Earth.

2. Analyze the presence of pollutants in the air: Students should learn that air is not only composed of gases essential to life, but also of pollutants that can be harmful. They should be able to identify and discuss different types of air pollutants.

3. Relate the composition of the air to natural phenomena and human activities: Students should understand how the composition of air can be affected by natural phenomena, such as the burning of fossil fuels, and by human activities, such as industrial pollution. They should be able to discuss the consequences of these changes in air composition.

Secondary Objectives:

• Develop research skills: Students should be able to search for information on air composition and air pollution in different sources, such as books, websites, and videos.
• Promote critical thinking: Students should be encouraged to question and analyze the information they find on air composition and air pollution. They should learn to form their own opinions and to express them respectfully in classroom discussions.

Introduction (10-15 minutes)

1. Review of necessary content: The teacher should start by reminding students about the importance of air for life on Earth, and how both breathing and photosynthesis depend on the presence of oxygen. In addition, the teacher should reinforce basic chemistry concepts, such as atoms, molecules, and the periodic table, which will be useful for understanding the composition of air. (3-5 minutes)

2. Problem situations: The teacher can present two situations that encourage students to think about the composition of air:

• First situation: "Why is it harder to breathe in some urban areas than in rural areas?" This question should lead students to think about the influence of air pollution on air quality.

• Second situation: "If air is colorless, odorless, and tasteless, how can we know that it exists and that its composition can vary?" This question should pique students' curiosity and encourage them to investigate the composition of air. (3-5 minutes)

3. Contextualization: The teacher should explain the importance of the composition of air for life on Earth, citing examples of how changes in the composition of air can affect climate, human health, and biodiversity. In addition, the teacher can mention the relevance of the topic to current events, considering the increase in air pollution and climate change. (2-3 minutes)

4. Capture the students' attention: The teacher can introduce the topic with interesting facts, such as:

• Fact 1: "Did you know that the composition of the air we breathe is very different from the composition of the air on other planets in our solar system? For example, on Mars, the air is almost entirely composed of carbon dioxide, a gas that is toxic to most living things on Earth."

• Fact 2: "Did you know that, although oxygen is essential for life on Earth, high concentrations of oxygen can be dangerous? At high altitudes, where atmospheric pressure is low, people can experience symptoms similar to drunkenness due to the high concentration of oxygen in the air." (3-5 minutes)

5. Introduction of the topic: The teacher should finally introduce the topic of the lesson - the composition of air - and explain that the lesson will focus on understanding what gases make up the air we breathe, how these gases can vary, and how the presence of pollutants can affect air quality. (1-2 minutes)

Development (20-25 minutes)

1. Playful Activity "Game of the Composition of the Air" (10-12 minutes)

• Materials needed: Colored cards, each representing a component of air (oxygen, nitrogen, carbon dioxide, argon, among others), and cards representing air pollutants (smoke, sulfur dioxide, carbon monoxide, among others).

• Preparation: The teacher should prepare the cards in advance, making sure that the proportions between the air components are correct. For example, if the air is composed of 78% nitrogen and 21% oxygen, there should be more nitrogen cards than oxygen cards.

• How to play: The students should be divided into groups of four. Each group receives a set of cards. The objective of the game is to recreate the composition of the air in a line, from the most abundant (nitrogen) to the least abundant (other gases). The groups should work together to organize the cards correctly. Then, they should add the air pollutant cards at different points in the line, discussing and justifying their decisions.

• Objectives: This activity aims to help students visualize the composition of the air and to understand how the addition of pollutants can change this composition. In addition, it promotes teamwork and discussion among students.

2. Practical Activity "Collecting and Analyzing Air" (10-13 minutes)

• Materials needed: Glass jars with lids, straws, nails, clips, thermometers, lamps, pH paper, litmus paper, among others.

• Preparation: The teacher should prepare the workstations, each containing the materials needed for the activity. The teacher should also provide clear instructions on how to use the materials safely.

• How to do it: The groups should follow the instructions provided by the teacher to collect air samples from different locations in the school, such as near a busy road, in a wooded area, near a factory, among others. They should record the location and time of collection of each sample. Then, they should analyze the samples using the materials provided, observing changes in temperature, acidity or alkalinity, and the presence of visible particles.

• Objectives: This activity aims to allow students to see, touch, and smell the air, reinforcing the idea that air is a real and tangible substance. In addition, it helps students to understand that the composition of air can vary in different locations and times, depending on factors such as the presence of pollutants and human activity.

3. Group discussion (5 minutes)

• How to do it: After completing the activities, the groups should come together for a group discussion. Each group should present their findings and conclusions to the class, and everyone should have the opportunity to ask questions and express their opinions.

• Objectives: This discussion aims to reinforce the concepts learned during the activities and to promote the exchange of ideas and critical thinking among students. In addition, it allows the teacher to assess students' understanding of the topic and to clarify any doubts that may arise.

Feedback (8-10 minutes)

1. Group Discussion (3-4 minutes)

• How to do it: After the hands-on activities, the teacher should facilitate a group discussion for the students to share their solutions or conclusions. Each group will have 3 minutes to present their main points, difficulties encountered, and reflections on the activity development.

• Objectives: This discussion will allow students to see different perspectives and approaches to the same problem, encouraging critical thinking and effective communication. Additionally, it is an opportunity for the teacher to evaluate students' understanding of the composition of air and the influence of pollutants.

2. Connection to Theory (2-3 minutes)

• How to do it: The teacher should then connect the hands-on activities to the theory, recalling the key concepts presented in the Introduction of the lesson and explaining how these concepts apply to the practical situations experienced by the students.

• Objectives: This moment of reflection will allow students to see the relevance of theory to practice and to understand how the concepts learned can be applied in real-life situations. It will also help to consolidate learning by reinforcing important concepts and clarifying any misunderstandings.

3. Self-Assessment (2-3 minutes)

• How to do it: To finalize the lesson, the teacher should have the students reflect on what they have learned and assess their own understanding of the topic. They can do this by answering questions like:

  • "What was the most important concept you learned today?"
  • "What questions were not answered yet?"

• Objectives: Self-assessment is a valuable tool for learning, as it helps students become aware of their own learning process. Also, by identifying any gaps in their understanding, the students will be better prepared for the upcoming lesson.

4. Teacher Feedback (1 minute)

• How to do it: The teacher should give the students a quick feedback, praising them for their efforts and contributions and reinforcing the main learning points of the lesson.

• Objectives: The teacher's feedback is a crucial tool for learning, as it helps to motivate students, reinforce what was learned and offer guidance for the future. Also, by providing feedback, the teacher can identify any areas that may need reinforcement in future lessons.

Conclusion (5-7 minutes)

1. Summary and Recapitulation (2-3 minutes)

• The teacher should start the conclusion by recalling the main points of the lesson. They should emphasize the composition of the air, the presence of pollutants, and how these can affect air quality.

• It should be reinforced the importance of nitrogen and oxygen in the air composition, and how the presence of other gases, even in small quantities, can alter the functioning of ecosystems.

• The teacher should also recall the hands-on activities carried out, highlighting the main results obtained by the students and how these relate to the theory presented.

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

• The teacher should explain how the lesson connected theory, practice and applications of the topic. They should emphasize that the knowledge acquired can be applied to understand everyday phenomena, such as air quality in different environments.

• It should be highlighted that the lesson was not only about learning facts, but also about developing critical thinking skills, teamwork and scientific investigation.

3. Extra Materials (1 minute)

• The teacher should suggest extra materials for students who want to dig deeper into the topic. These materials could include educational videos, science websites, books, and documentaries about the composition of the air and air pollution.

4. Relevance of the Subject (1 minute)

• To conclude, the teacher should highlight the relevance of the topic for the students' daily lives. They can mention how understanding the composition of the air can help to understand the importance of preserving the environment and the need to reduce air pollution.

• In addition, they can emphasize that the topic is of great importance to society as a whole, considering current challenges such as climate change and air pollution, which require collective action to protect human health and the environment.