Objectives (5 - 7 minutes)

1. Understand the concept of Molarity: The teacher must ensure that students understand what molarity is and how it is calculated. Students should be able to define molarity and identify the appropriate unit of measurement.

2. Apply the Molarity formula: Students should be able to apply the molarity formula to solve practical problems. They should understand how to use the formula and be able to identify the variables needed for the calculation.

3. Solve problems involving Molarity: In addition to understanding the theory and the formula, students should be able to solve problems involving the calculation of molarity. This includes the ability to interpret the problem, identify relevant information, and apply the formula correctly.

   Secondary Objectives:

   • Review previous concepts: The teacher should review previous concepts, such as the definition of moles and the relationship between moles, mass, and volume, to ensure that students have the necessary foundation to understand molarity.

   • Encourage active participation: The teacher should encourage active participation from students during the lesson, whether through questions, discussions, or practical activities. This will help ensure that students are engaged and understanding the content.

Introduction (10 - 15 minutes)

1. Review of previous concepts: The teacher should start the lesson by reviewing the concepts of mole, moles, mass, and volume, which are fundamental to understanding the topic of molarity. This can be done through a brief discussion, questions to the class, or a small quiz. This step is essential to ensure that students have the necessary foundation to understand and absorb the new content.

2. Problem situations: Next, the teacher should present two problem situations involving the concept of molarity. For example:

   • "If you have a liter of a solution containing 0.5 moles of salt, what is the molarity of this solution?"
   • "If you have a liter of a solution containing 0.25 moles of glucose, what is the molarity of this solution?"

   These problem situations will serve as a starting point for the introduction of the concept of molarity and the application of the formula.

3. Contextualization: The teacher should then contextualize the importance of molarity, explaining how it is used in various areas such as medicine, the pharmaceutical industry, and the chemical industry. For example, molarity is used to determine the concentration of a substance in a solution, which can be crucial for the effectiveness of a medication or the performance of a chemical product.

4. Introduction to the topic: Finally, the teacher should introduce the topic of molarity, explaining what it is and what it is used for. Everyday examples can be used to make the subject more concrete and relevant to students. For example:

   • "You must have heard of 'warm water', right? But what does that really mean? Well, 'warm water' is a solution that has a certain amount of thermal energy, in other words, a certain molarity. And it is this molarity that determines whether the water is more towards hot or cold."

   • "Another example is lemon juice. When we add sugar to the juice, it becomes sweeter, right? That's because sugar increases the molarity of the juice, that is, the concentration of 'sweetness' in the solution."

   This Introduction should spark students' curiosity and prepare them for a more in-depth study of the topic.

Development (20 - 25 minutes)

1. Activity 'Creating a Solution': Students will be divided into groups of up to five people. Each group will receive a set of materials (cups, water, salt, spoons, etc.) to create a solution with a specific molarity. The teacher will provide a spreadsheet with different molarities (for example, 0.5 M, 1 M, 2 M, etc.) and the groups will have to choose one and create the corresponding solution. They will have to calculate the amount of salt and water needed and then prepare the solution. The activity will be guided by the Molarity formula: M = n/V, where M is the molarity, n is the number of moles of the substance, and V is the volume of the solution. The teacher will circulate around the room, assisting the groups and clarifying doubts.

   • Step 1: The teacher presents the activity and distributes the materials to the groups.
   • Step 2: The groups choose the molarity of the solution they want to create.
   • Step 3: The groups calculate the amount of salt and water needed for the chosen molarity.
   • Step 4: The groups prepare the solution and present it to the rest of the class, explaining the process they followed.
   • Step 5: The teacher reviews the calculations of each group and verifies if the solutions were prepared correctly.

2. Activity 'Molarity Problems': After the conclusion of the previous activity, the groups will receive a series of molarity problems to solve. The problems will be based on real situations and will involve calculating molarity from information such as the number of moles and the volume of the solution. The groups will have to apply the molarity formula to solve the problems. The teacher will circulate around the room, monitoring the progress of the groups and clarifying doubts.

   • Step 1: The teacher distributes the molarity problems to the groups.
   • Step 2: The groups read and interpret the problems.
   • Step 3: The groups apply the molarity formula to solve the problems.
   • Step 4: The groups present their solutions and the process they followed to solve them.
   • Step 5: The teacher reviews the solutions of each group and clarifies any remaining doubts.

3. Activity 'Group Discussion': After solving the problems, each group will choose a problem to discuss with the class. They should explain the problem, how they solved it, and what difficulties they encountered. This activity aims to promote discussion and exchange of ideas among students, reinforcing the understanding of the concept of molarity.

   • Step 1: Each group chooses a problem to discuss with the class.
   • Step 2: The groups prepare a quick presentation, explaining the problem, the resolution process, and the difficulties encountered.
   • Step 3: The groups present their discussions to the class.
   • Step 4: The teacher facilitates the discussion, asking questions and clarifying doubts.
   • Step 5: The teacher reinforces the concepts learned and concludes the activity.

Return (8 - 10 minutes)

1. Group Discussion: The teacher should promote a group discussion with all students. Each group will have 2 minutes to share the solutions they found for the proposed problems. During this discussion, the teacher should encourage students to explain the reasoning behind their answers and discuss different approaches to solving the problems. This will help reinforce learning and identify possible gaps or misunderstandings. (Estimated time: 5 minutes)

   • Step 1: The teacher encourages groups to share their solutions and discuss different approaches.
   • Step 2: The teacher asks questions to clarify students' reasoning and reinforce molarity concepts.
   • Step 3: Students respond to the questions and continue the discussion, if necessary.

2. Connection with Theory: The teacher should then make the connection between practical activities and theory. They should explain how the molarity formula was applied to solve the problems and how the concepts of mole, moles, mass, and volume were used. This will help students understand the relevance of the theory and the applicability of the concepts learned. (Estimated time: 2 minutes)

   • Step 1: The teacher recaps the molarity formula and how it was used to solve the problems.
   • Step 2: The teacher reinforces the concepts of mole, moles, mass, and volume and how they relate to molarity.

3. Final Reflection: To end the lesson, the teacher should propose that students reflect individually for one minute on what they have learned. They can ask questions like:

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

   After the reflection, students will have the opportunity to share their answers with the class, if they wish. This will allow the teacher to assess the level of understanding of the students and identify any areas that may need review or reinforcement in future classes. (Estimated time: 3 minutes)

   • Step 1: The teacher proposes reflection questions.
   • Step 2: Students reflect individually for one minute.
   • Step 3: The teacher invites students to share their answers, if they wish.
   • Step 4: The teacher concludes the lesson, thanking the students for their participation and reinforcing the concepts learned.

Conclusion (5 - 7 minutes)

1. Content Summary: The teacher should give a brief summary of the content covered in the lesson, reinforcing the main concepts and molarity formulas. This will serve to consolidate students' learning and ensure they have understood the key points of the topic. For example, recapitulating the definition of molarity, the formula M = n/V, and the relationship between mole, moles, mass, and volume. (Estimated time: 2 minutes)

2. Connection between Theory, Practice, and Applications: The teacher should explain how the lesson connected theory, practice, and the applications of molarity concepts. They should highlight how the 'Creating a Solution' activity allowed students to apply the molarity formula in a practical and concrete way, and how the subsequent discussion helped deepen students' understanding. Additionally, the teacher should reinforce the importance of molarity in various application areas, such as medicine and the chemical industry. (Estimated time: 2 minutes)

3. Additional Materials: The teacher should suggest additional study materials for students who wish to deepen their knowledge of molarity. This may include textbooks, chemistry websites, educational videos, among others. For example, recommending a practical molarity experiment that students can do at home, or an explanatory video that reinforces the concepts learned. (Estimated time: 1 minute)

4. Subject Importance: Finally, the teacher should emphasize the importance of the subject for students' daily lives. For example, mentioning how understanding molarity can be useful for understanding everyday phenomena, such as the taste of food or the effectiveness of a medication. Additionally, the teacher can emphasize how the ability to solve molarity problems can be valuable in various careers, such as medicine, food engineering, forensic chemistry, among others. (Estimated time: 1 minute)

   • Step 1: The teacher highlights the main concepts and molarity formulas.
   • Step 2: The teacher explains the connection between theory, practice, and the applications of molarity concepts.
   • Step 3: The teacher suggests additional study materials.
   • Step 4: The teacher emphasizes the importance of the subject for daily life and students' careers.
   • Step 5: The teacher concludes the lesson, thanking the students for their participation and encouraging them to continue studying the subject.