Objectives (5 - 7 minutes)

1. Understand the concept of optical isomerism and its importance in the study of organic chemistry.
2. Identify and distinguish between optical isomers, focusing on the difference in the rotation of the plane of polarization of light.
3. Apply the acquired knowledge to solve problems and questions related to optical isomerism, including determining the quantity of enantiomers in a sample.

Secondary Objectives:

• Develop logical and critical thinking skills to analyze and solve problems related to optical isomerism.
• Promote communication skills by discussing and explaining concepts and answers during exercise resolution.
• Stimulate curiosity and interest in organic chemistry, demonstrating the practical application of optical isomerism in various areas such as pharmaceuticals and food.

Introduction (10 - 12 minutes)

1. Review of previous concepts (3 - 4 minutes)

   • The teacher starts the lesson by reviewing concepts of chemical bonds, molecular structures, and the idea of isomerism.
   • It is important for students to understand the difference between structural isomerism and optical isomerism, as the former was covered in previous classes and the latter will be the focus of this lesson.
   • The teacher can ask quick questions to assess students' understanding of these concepts before proceeding.

2. Problem situations (3 - 4 minutes)

   • The teacher presents two problem situations to contextualize the importance of optical isomerism. For example, how can two substances with the same molecular formula have different physical and chemical properties? And how does the pharmaceutical industry use optical isomerism to produce medications?
   • The goal of these problem situations is to arouse students' curiosity and prepare them for the lesson topic.

3. Contextualization (2 - 3 minutes)

   • The teacher demonstrates how optical isomerism is applied in everyday life and in various industries. For example, in the food industry, optical isomerism is used to produce sweeteners and flavorings. In the pharmaceutical industry, it is used to produce medications with specific effects, such as the case of ibuprofen and its isomer, dexibuprofen.
   • The teacher can also mention the importance of optical isomerism in biochemistry, as most amino acids that make up proteins are optical isomers.

4. Introduction to the topic (2 - 3 minutes)

   • To introduce the lesson topic, the teacher can ask the following question: 'Have you ever heard that light can be 'polarized'? What do you understand by that?'.
   • The teacher then explains that light is an electromagnetic wave that normally propagates in all directions but can be manipulated to propagate in a specific direction, a phenomenon called light polarization.
   • The teacher then introduces the concept of optical isomerism, explaining that certain substances have the ability to rotate the plane of polarization of light and that this property is used to distinguish between optical isomers.

Development (20 - 25 minutes)

1. Theory of Optical Isomerism (5 - 7 minutes)

   • The teacher begins the explanation of the theoretical content by presenting the definition of optical isomerism, which is the property that some substances have to rotate the plane of polarization of light.
   • The teacher then explains that substances that possess this property are called 'chiral' and that optical isomerism occurs when a molecule is asymmetric, meaning it does not have a plane of symmetry.
   • The teacher can use molecular models or illustrations to exemplify chiral and non-chiral molecules.
   • Finally, the teacher explains that in a sample of a chiral substance, there are two different forms of the same substance, which are enantiomers, and that these enantiomers have the ability to rotate the plane of polarization of light in opposite directions and are therefore classified as dextrorotatory or levorotatory.

2. Method of Determining Optical Isomers (5 - 7 minutes)

   • The teacher explains that the rotation of the plane of polarization of light caused by an enantiomer can be measured using a polarimeter.
   • The teacher can show images and drawings of a polarimeter and explain how it works. For example, how light passes through the sample in the sample tube and is deviated, and how the magnitude of this deviation is measured by the polarimeter.
   • The teacher can also briefly discuss the equation used to calculate the specific rotation of a chiral substance.
   • The teacher then explains that to determine the quantity of enantiomers in a sample, it is necessary to analyze the rotation of the plane of polarization of light caused by the sample using a polarimeter, and that this is done in practice by chemists in laboratories.

3. Practical Examples and Applications (5 - 7 minutes)

   • The teacher presents practical examples to illustrate the application of optical isomerism. For example, the teacher can show images of medications that are racemic mixtures, containing equal amounts of each enantiomer, and explain that in some cases, one enantiomer can be more active than the other, which can lead to unwanted side effects or a reduction in the effectiveness of the medication.
   • The teacher can also discuss examples of applications of optical isomerism in other areas, such as in the production of food and beverages, in the perfume and flavor industry, and in the polymer industry.
   • The teacher can encourage students to think of more examples of applications of optical isomerism and discuss these examples in the classroom.

4. Exercise Resolution (5 - 7 minutes)

   • The teacher proposes the resolution of exercises to consolidate students' understanding of the presented content. The exercises may include the identification of chiral substances, the determination of the quantity of enantiomers in a sample, and the interpretation of problem situations involving optical isomerism.
   • During the resolution of the exercises, the teacher should be available to answer questions and provide guidance when necessary.
   • At the end of the exercise resolution, the teacher can discuss the answers with the class and clarify any remaining doubts.

Return (8 - 10 minutes)

1. Group Discussion (3 - 4 minutes)

   • The teacher suggests that students divide into small groups to discuss the solutions to the proposed exercises.
   • Each group should have the opportunity to share their answers and explain the reasoning behind them to the class.
   • The teacher should encourage the participation of all students and ensure that the discussions are respectful and constructive.

2. Connection with Theory (2 - 3 minutes)

   • After the group discussions, the teacher should review the presented theoretical concepts and connect them to the exercise solutions.
   • The goal is to ensure that students understand how to apply the theory in practice and how the concepts of optical isomerism are used to solve problems and questions.

3. Individual Reflection (2 - 3 minutes)

   • The teacher then proposes that students reflect individually on what they learned in the lesson.
   • The teacher can ask guiding questions, such as: 'What was the most important concept you learned today?' and 'What questions have not been answered yet?'.
   • Students should have a minute to think about these questions and then will be invited to share their answers with the class.
   • The teacher should listen carefully to students' answers and note any questions or difficulties that may need clarification in future classes.

4. Feedback and Closure (1 - 2 minutes)

   • The teacher concludes the lesson by thanking the students for their participation and asking for feedback on the lesson.
   • The teacher can ask: 'Did you find optical isomerism difficult to understand? What could have been done differently to facilitate learning?'.
   • Student feedback is important so that the teacher can adjust their teaching approach and ensure that future lessons are effective and engaging.
   • The teacher can also take this opportunity to reinforce the importance of optical isomerism and to encourage students to continue studying the subject and to ask questions if they have doubts.

Conclusion (5 - 7 minutes)

1. Review of Concepts (2 - 3 minutes)

   • The teacher starts the Conclusion of the lesson by recapping the main points covered.
   • The concept of optical isomerism is reinforced, as well as the idea that some substances have the property of rotating the plane of polarization of light and are called chiral.
   • The teacher recalls that in a sample of a chiral substance, there are two enantiomers, which are different forms of the same substance, with the ability to rotate the plane of polarization of light in opposite directions.

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

   • The teacher highlights how the lesson connected theory, practice, and applications of optical isomerism.
   • The teacher reiterates that besides understanding the concept of optical isomerism, students also learned to apply this knowledge to solve problems and questions, such as determining the quantity of enantiomers in a sample.
   • The teacher can emphasize again the examples of applications of optical isomerism presented during the lesson and reinforce the importance of this property in various areas, such as pharmaceuticals and food.

3. Extra Materials (1 - 2 minutes)

   • The teacher suggests extra materials for students who wish to deepen their knowledge of optical isomerism.
   • These materials may include organic chemistry books, scientific articles on the subject, educational videos available on the internet, and additional exercises to practice determining the quantity of enantiomers in a sample.
   • The teacher can provide a list of these materials at the end of the lesson or send it to students via email.

4. Importance of the Subject (1 minute)

   • The teacher concludes the lesson by emphasizing the importance of the subject for students' daily lives.
   • The teacher can mention again the applications of optical isomerism, such as in the production of medications, food and beverages, and the perfume and flavor industry.
   • Additionally, the teacher can highlight how understanding optical isomerism can help students better comprehend organic chemistry and biochemistry, areas of study that are present in various everyday situations and in several professions.