Objectives (5 - 7 minutes)

1. Introduce the concept of value equivalence, which is the basis for understanding buying and selling. The teacher should explain that value equivalence is when two or more things have the same value. This can be applied to numbers, quantities, and even money.

2. Teach students the difference between buying and selling and how these two actions are interconnected. The teacher should explain that buying is when someone acquires something in exchange for money or another good, while selling is when someone offers something to be acquired in exchange for money or another good.

3. Provide problem situations involving the buying and selling of objects, so that students can apply what they have learned about value equivalence. The teacher should create simple and concrete problem situations related to students' daily lives that can be solved using basic math operations.

Introduction (10 - 15 minutes)

1. Review of Previous Content: The teacher should start the lesson by reviewing basic math concepts such as numbers, quantities, and addition and subtraction operations. This is important because these concepts will be fundamental for understanding the lesson topic. The teacher can propose some quick review activities, such as counting from 1 to 10, solving simple addition and subtraction problems, and comparing quantities.

2. Problem Situations: The teacher should then present two problem situations related to students' daily lives that involve buying and selling objects. For example, the teacher can ask: 'If you have $10.00 and want to buy a toy that costs $5.00, how much will you have left from your money?' and 'If you have 2 apples and want to sell 1, how many apples will you have after the sale?'. These problem situations serve to spark students' interest and to contextualize the lesson topic.

3. Contextualization: The teacher should then explain to the students that math is present in many everyday situations, including when buying and selling things. The teacher can mention simple examples, such as going to the bakery to buy bread, or trading stickers with classmates. The goal is to show students that what they will learn in the lesson is very useful and practical.

4. Introducing the Topic: To introduce the lesson topic, the teacher can ask two questions: 'Have you ever stopped to think about how shopkeepers decide the price of a product?' and 'Have you ever wondered why some things cost more than others?'. These questions serve to arouse students' curiosity and prepare them for what they will learn in the lesson.

5. Capturing Students' Attention: The teacher can then share two curiosities to capture students' attention. The first is that in the past, people did not use money to buy and sell things, they used direct exchange, for example, an apple for an orange. The second curiosity is that in the past, money had a very different value from what it has today. For example, a $1.00 bill today can buy many things, but in the past a $1.00 coin bought almost nothing. These curiosities serve to arouse students' interest and to show the importance of time and value in buying and selling things.

Development (20 - 25 minutes)

1. Explanation of Value Equivalence (5 - 7 minutes):

   • The teacher should start by explaining that value equivalence is when two or more things have the same value. They can use concrete examples, such as exchanging one toy for another, or exchanging a snack for a fruit.
   • Next, the teacher should explain that value equivalence can also be applied to numbers and quantities. For example, 2 oranges can be equivalent to 4 apples, or $10 can be equivalent to 2 $5 bills.
   • The teacher can reinforce the concept of value equivalence with some practical activities, such as asking students to compare the value of different coins or bills, or to compare the value of two sets of fruits.

2. Understanding Buying and Selling (5 - 7 minutes):

   • The teacher should then explain the difference between buying and selling. They can use simple examples, such as buying a toy at the store or selling a drawing to a classmate.
   • The teacher can use real situations to illustrate the concept, such as buying a snack at the school cafeteria or selling a book at the library.
   • The teacher should emphasize that both buying and selling involve an exchange of values. In buying, the student exchanges their money for a product or service. In selling, the student exchanges a product or service for money.

3. Application of Value Equivalence in Buying and Selling (10 - 11 minutes):

   • The teacher should then explain how value equivalence is used in buying and selling. They can use simple examples, such as exchanging a $10 bill for two $5 bills, or exchanging 3 apples for 6 oranges.
   • The teacher can propose some simple problem situations that involve the application of value equivalence in buying and selling. For example, the teacher can ask: 'If a toy costs $5, how many toys can I buy with $20?'.
   • The teacher should encourage students to solve the problem situations using the knowledge they have acquired about value equivalence. They can guide students to draw or use concrete materials, such as coins and bills, to help them visualize the value exchanges.

4. Connection to Theory (5 - 7 minutes):

   • The teacher should then review the presented theory and make a summary of the content. They can use simple examples, such as exchanging an apple for an orange, to reinforce the concept of value equivalence.
   • The teacher can ask some questions to check students' understanding. For example, the teacher can ask: 'What is value equivalence?' and 'How can we apply value equivalence in buying and selling?'.
   • The teacher should correct any misunderstandings and reinforce the key points of the lesson. They can use additional examples, if necessary, to help students understand the concept.

Return (10 - 15 minutes)

1. Group Discussion (5 - 7 minutes):

   • The teacher should gather all students in a large circle and promote a group discussion about the solutions found for the proposed problem situations.
   • Each group of students should share how they arrived at their answers, what strategies they used, and what difficulties they encountered during the process.
   • The teacher should guide the discussion by asking questions to stimulate critical thinking and reflection. For example, the teacher can ask: 'Why do you think this strategy worked?' and 'What would you do differently next time?'.

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

   • After the discussion, the teacher should review the theoretical concepts discussed in the lesson and check how they were applied in the solutions found by the students.
   • The teacher should highlight the strategies and solutions that best exemplify the application of value equivalence in buying and selling.
   • The teacher can ask questions like: 'How did you use value equivalence to solve the problem?' and 'Can you think of another situation where value equivalence can be applied?'.

3. Individual Reflection (2 - 3 minutes):

   • To conclude the lesson, the teacher should propose that students make an individual reflection on what they have learned.
   • The teacher can ask two simple questions to guide students' reflection: 'What was the easiest thing to understand in today's lesson?' and 'What was the most difficult thing to understand and why?'.
   • Students should have a minute to reflect on these questions. If desired, the teacher can ask some students to share their answers with the class.

4. Teacher Feedback (1 minute):

   • At the end of the lesson, the teacher should give overall feedback on students' performance, highlighting strengths and areas that need more attention.
   • The teacher can praise students' efforts in solving the problem situations, active participation in the group discussion, and understanding of the value equivalence concept.
   • At the same time, the teacher can identify which points of the lesson need to be reviewed or deepened, based on students' responses during the discussion and individual reflection.

This return is a crucial moment to consolidate students' learning, promoting reflection, discussion, and connection to theory. Additionally, it allows the teacher to assess the effectiveness of the lesson and make necessary adjustments for future classes.

Conclusion (5 - 7 minutes)

1. Summary of Contents (2 - 3 minutes):

   • The teacher should start the conclusion by recalling the main concepts covered in the lesson. They can emphasize the importance of value equivalence in mathematics and daily life, explaining that it is a key concept for understanding buying and selling.
   • The teacher should recall the definition of buying and selling, explaining that buying is when a person acquires something in exchange for money or another good, while selling is when a person offers something to be acquired in exchange for money or another good.
   • Finally, the teacher should reinforce the practical application of these concepts, reminding students that they can use what they have learned to solve everyday problems involving the buying and selling of objects.

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

   • The teacher should then explain how the lesson connected theory, practice, and applications. They can say that through problem situations and practical activities, students were able to apply the learned theory in a concrete and meaningful way.
   • The teacher can emphasize that the ability to solve buying and selling problems is very useful in everyday life, as it helps in making financial decisions and in developing logical and critical thinking.

3. Extra Materials (1 minute):

   • The teacher should suggest some extra materials for students who wish to deepen their knowledge on the topic. This may include textbooks, educational websites, math games, and apps.
   • For example, the teacher can recommend the 'Khan Academy' website, which offers a wide variety of videos and exercises on mathematics, including topics related to buying and selling.
   • Additionally, the teacher can suggest that students practice at home by solving buying and selling problems with real or fictional coins and bills.

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

   • Finally, the teacher should conclude the lesson by explaining the importance and relevance of what was learned. They can say that the ability to understand and apply value equivalence is essential knowledge for life, as it helps us make prudent financial decisions and better understand the world around us.
   • The teacher can mention concrete examples, such as the importance of comparing prices and making smart choices during shopping, or the importance of understanding the value of money to plan and save for the future.
   • Lastly, the teacher can emphasize that by learning math in a fun and practical way, students are developing valuable skills that will benefit them in many aspects of their lives.

This conclusion allows the teacher to reinforce the main points of the lesson, encourage the search for knowledge outside the classroom, and show students the importance and relevance of what they have learned. Additionally, it helps to end the lesson on a positive and motivating note, leaving students excited to learn more.