Objectives (5 - 7 minutes)

1. Understand the Concept of Molar Fraction: Students should be able to understand the concept of molar fraction and its importance in Chemistry. It should be explained that the molar fraction of a component in a mixture is the ratio between the number of moles of that component and the total number of moles in the mixture.

2. Calculate Molar Fraction: Students should be able to calculate the molar fraction of a component in a mixture. This involves identifying the amount of moles of a specific component and dividing by the total number of moles in the mixture.

3. Apply Molar Fraction in Practical Problems: Students should be able to apply the concept of molar fraction to solve practical problems. This may include determining the concentration of a component in a mixture, based on its molar fraction.

   Secondary Objectives:

   • Develop Critical Thinking: When solving problems involving molar fraction, students should be encouraged to develop critical thinking, identifying the necessary steps to reach a solution.
   • Promote Group Work: The use of the inverted classroom model promotes interaction among students, encouraging group work and collaboration.
   • Stimulate Autonomous Learning: By taking responsibility for their own learning, students are encouraged to develop autonomous study skills.

Introduction (10 - 15 minutes)

1. Review of Previous Content:

   • The teacher should start the lesson with a brief recap of the concepts of mole and molarity, as these are fundamental to understanding the current topic.
   • It is important for students to have a good understanding of these concepts before moving on to molar fraction. The teacher can remind students that the mole is a unit that represents an amount of substance and that molarity is the amount of moles of solute dissolved in one liter of solution.

2. Problem Situation:

   • The teacher can propose two problem situations to instigate students' interest and introduce the topic. For example:
     1. "Imagine you have two bottles, one containing 10 moles of CO2 and the other 5 moles of H2O. If you mix them, how can you calculate the molar fraction of each component in the resulting mixture?"
     2. "If you have a mixture of 20 moles of CO2 and 30 moles of H2O, how can you calculate the molar fraction of each component?"

3. Contextualization:

   • The teacher should explain the importance of molar fraction in chemistry, emphasizing that it is used to express the concentration of a component in a mixture.
   • Practical examples can be mentioned, such as determining the concentration of oxygen and nitrogen in the Earth's atmosphere, or determining the amount of ethanol and water in an alcoholic beverage.

4. Introduction to the Topic:

   • The teacher can introduce the topic of molar fraction in an engaging way, for example, mentioning that it is like "dividing the chemical cake", or "calculating the slice of each component in the chemical pizza".
   • Another interesting approach is to show students that molar fraction is a way to describe the "participation" of each component in a mixture, similar to how shares in a company can be described in terms of "percentage participation".

By the end of this stage, students should be familiar with the concept of molar fraction, understanding that it is a ratio between the number of moles of a component and the total number of moles in the mixture.

Development (20 - 25 minutes)

1. Modeling Activity: "Dividing the Chemical Cake"

   • Description: The teacher will propose the activity "Dividing the Chemical Cake", in which students will represent a mixture (the cake) and its components (the cake slices) using different colored modeling clay. Each color will represent a different component of the mixture.

   • Step by Step:

     1. The teacher should divide the class into groups of up to 5 students and provide each group with modeling clay of 2 different colors.
     2. Each group should create a mixture (the cake) with the two colors of modeling clay, with each color representing a component.
     3. Then, students should calculate the molar fraction of each component of the mixture and represent it by dividing the cake into equal parts, according to the calculated molar fraction.
     4. Students should record the calculation steps and the final result, noting the molar fractions on a piece of paper.
     5. At the end of the activity, each group should present their "Chemical Cake" and explain how they calculated the molar fraction of each component.

   • Learning Objective: This activity aims to allow students to visualize the concept of molar fraction and practice calculating this concentration unit in a playful and meaningful way.

2. Problem-Solving Activity: "Chemical Pizza"

   • Description: The teacher will propose the activity "Chemical Pizza", in which students will solve molar fraction calculation problems in a more complex and realistic context.

   • Step by Step:

     1. The teacher should provide each group with a list of ingredients for a pizza (the mixture) and the quantities of each ingredient (the components).
     2. Students should calculate the molar fraction of each ingredient and record the results.
     3. Then, the teacher should propose different scenarios, such as "if we add more cheese, how will it affect the molar fraction of each ingredient?" or "if we remove the tomato, how will it affect the molar fraction of each ingredient?".
     4. Students should perform new molar fraction calculations, taking into account the proposed changes.
     5. At the end of the activity, each group should present their calculations and the conclusions drawn.

   • Learning Objective: This activity aims to allow students to apply the concept of molar fraction in solving practical problems, developing the ability to think critically and work in a group.

By the end of this stage, students should be able to calculate the molar fraction of a component in a mixture and apply this concept to solving practical problems. Additionally, they should have developed critical thinking and group work skills.

Feedback (10 - 15 minutes)

1. Group Discussion:

   • The teacher should promote a group discussion, where each group will present the solutions or conclusions found during the activities "Dividing the Chemical Cake" and "Chemical Pizza".
   • The teacher should encourage students to explain how they reached their solutions, what difficulties they encountered, and how they overcame them.
   • The teacher should also clarify any doubts that may have arisen during the presentations.

2. Connection with Theory:

   • After the presentations, the teacher should make the connection between the practical activities carried out and the theory of molar fraction.
   • The teacher should reinforce the concept of molar fraction, explaining again that it is the ratio between the number of moles of a component and the total number of moles in the mixture.
   • The teacher should also emphasize the importance of molar fraction in determining the concentration of a component in a mixture.

3. Individual Reflection:

   • The teacher should propose that students reflect individually on what they learned during the lesson.
   • To do this, the teacher can ask questions like:
     1. "What was the most important concept you learned today?"
     2. "What questions have not been answered yet?"
   • Students should have a minute to think and then can share their answers with the class.
   • The teacher should listen carefully to students' answers, as they can provide valuable feedback on students' understanding and possible gaps in learning.

4. Teacher's Feedback:

   • Based on students' answers and observations during the lesson, the teacher should provide feedback on students' performance.
   • The teacher should praise the successes, highlight strengths, and suggest areas that need improvement.
   • The teacher should also answer any unanswered questions and clarify any remaining doubts.

By the end of this stage, students should have had the opportunity to reflect on what they learned, ask questions, and receive feedback on their performance. This is important for consolidating learning and identifying possible gaps in knowledge, which can be addressed in future lessons.

Conclusion (5 - 7 minutes)

1. Content Summary:

   • The teacher should give a brief summary of the main points covered in the lesson, reinforcing the concept of molar fraction and how it is calculated.
   • The importance of molar fraction for determining the concentration of a component in a mixture should be highlighted.
   • The teacher can use practical examples again to illustrate the concept, such as determining the amount of alcohol in an alcoholic beverage.

2. Connection between Theory and Practice:

   • The teacher should emphasize how the lesson connected the theory of molar fraction with practice, through the activities "Dividing the Chemical Cake" and "Chemical Pizza".
   • It should be emphasized how understanding the concept of molar fraction allowed students to solve practical problems efficiently.

3. Extra Materials:

   • The teacher can suggest extra materials for students who wish to deepen their knowledge of molar fraction.
   • These materials may include explanatory videos, scientific articles, additional exercises, among others.
   • The teacher should make these materials available so that students can easily access them, either through an online platform or through printed copies.

4. Importance of the Subject:

   • Finally, the teacher should reinforce the importance of the subject presented for everyday life and for other areas of knowledge.
   • It should be emphasized that the concept of molar fraction is widely used in Chemistry, especially in the area of solutions, and that the ability to calculate and understand molar fraction is fundamental for those who wish to pursue a career in natural sciences, engineering, medicine, among other areas.
   • The teacher can also mention that molar fraction can be used in everyday situations, such as diluting cleaning chemicals or preparing food and beverages.

By the end of this stage, students should have consolidated their understanding of the concept of molar fraction and understood its importance in Chemistry. Additionally, they should feel motivated to continue studying the subject, either through the suggested extra materials or through the application of the concept in everyday situations.