Objectives (5 - 7 minutes)

1. Understand the concept of arithmetic mean: Students should be able to understand what arithmetic mean is and how it is calculated. This includes understanding that the mean is the sum of all values divided by the total number of values.

2. Apply arithmetic mean in different situations: After understanding the concept, students should be able to apply arithmetic mean in practical situations. They should learn how to calculate the mean of a set of numbers and interpret the result.

3. Recognize the importance of arithmetic mean in everyday life: Students should be able to identify examples of where arithmetic mean is used in daily life. This may include situations such as calculating the average grades in a class, or the average ages in a population.

Secondary Objectives

• Develop problem-solving skills: Through the use of arithmetic mean in practical problems, students should be able to develop and enhance their problem-solving skills.

• Promote critical thinking: When working with arithmetic mean, students should be encouraged to think critically about the data they are manipulating and the results they are obtaining.

Introduction (10 - 12 minutes)

1. Review of previous concepts: The teacher should start the lesson by reviewing the concepts of addition, subtraction, multiplication, and division. These concepts are fundamental to understanding arithmetic mean. The teacher can ask students to share examples of when they have used these operations and briefly discuss how they relate to arithmetic mean. (3 - 4 minutes)

2. Problem situation 1: The teacher can present the following situation: "Imagine you are in a candy store and want to calculate the average prices of various types of candies. How would you do that?" This situation is designed to spark students' interest and to show the relevance of arithmetic mean in everyday situations. (2 - 3 minutes)

3. Contextualization: The teacher should then explain that arithmetic mean is often used in various areas, such as sports (to calculate the average scores of players), finance (to calculate the average prices of stocks over a certain period of time), and science (to calculate the average of repeated measurements in an experiment). The teacher can briefly share examples of how the mean is used in different contexts. (2 - 3 minutes)

4. Presentation of the topic: The teacher should then introduce the concept of arithmetic mean, explaining that it is a way to represent a set of numbers by a single number, which is its mean. The teacher can show the formula for arithmetic mean (sum of all values divided by the total number of values) and explain each part of it. The teacher can then say that during the lesson, students will learn how to calculate arithmetic mean and apply it in different situations. (2 - 3 minutes)

5. Problem situation 2: To conclude the Introduction and prepare students for the next stage of the lesson, the teacher can present another situation: "Imagine you are in a classroom and want to calculate the average grades of several students. How would you do that?" This situation is designed to challenge students to think about how they will apply what they have learned in the lesson. (1 minute)

Development (20 - 25 minutes)

1. Activity 1 - Building the Mean: (8 - 10 minutes)

   • Description: The teacher will divide the class into groups of 3 to 4 students. Each group will receive a set of cards of different colors. Each card will have a number. The numbers can range from 1 to 10. Students must arrange the cards in ascending order of value.

   • Step by step:

     1. The teacher distributes the cards to each group.
     2. Students arrange the cards in ascending order of value.
     3. Once the cards are organized, students must add up all the values and divide the result by the total number of cards to find the mean.
     4. Each group should check if their mean calculation is correct.
     5. The teacher circulates around the room, helping groups that are struggling and clarifying any doubts.

   • Objective: This activity aims to allow students to visualize and understand the process of calculating arithmetic mean. Additionally, they will have the opportunity to work in teams and discuss their findings.

2. Activity 2 - The Mean Game: (10 - 12 minutes)

   • Description: The teacher prepares in advance worksheets with 10 problems that involve calculating arithmetic mean. The problems can be of different levels of difficulty. Each group receives a worksheet and must solve it within a set time.

   • Step by step:

     1. The teacher hands out a worksheet to each group.
     2. Students, in their groups, work together to solve the problems. They must calculate the mean for each set of numbers provided and write the answer on the worksheet.
     3. The group that finishes first and has the most correct answers wins the game.
     4. The teacher reviews the answers with the class and clarifies any doubts.

   • Objective: This activity aims to provide students with the opportunity to apply what they have learned about arithmetic mean in a fun and challenging context. Additionally, they will have the chance to improve their problem-solving skills and teamwork.

3. Activity 3 - Group Discussion: (2 - 3 minutes)

   • Description: To conclude the Development stage, the teacher promotes a group discussion about the solutions found by students in the previous activities. The teacher can ask questions like: "How did you decide to organize the cards in Activity 1?" or "What strategies did you use to solve the problems in Activity 2?".

   • Step by step:

     1. The teacher gathers the class and asks each group to share their experiences and learnings.
     2. The teacher facilitates the discussion by asking questions to deepen students' understanding and connecting the concepts learned with practice.
     3. The teacher emphasizes the importance of arithmetic mean in everyday life and how it can be applied in different situations.

   • Objective: This activity aims to consolidate students' learning, allowing them to reflect on what they have learned and how they can apply their new knowledge. Additionally, group discussion helps develop communication and critical thinking skills.

Return (8 - 10 minutes)

1. Group Discussion 1: (3 - 4 minutes)

   • Description: The teacher asks each group to share their solutions to the problems from Activity 2. Each group will have a maximum of 2 minutes to present. During the presentations, the teacher should encourage other groups to ask questions and make comments.
   • Step by step:
     1. The teacher calls the first group to present their solutions.
     2. After the first group's presentation, the teacher opens for questions and comments from the other groups.
     3. The process is repeated for the other groups.
     4. The teacher concludes the discussion ensuring that all key points were addressed.

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

   • Description: The teacher should then make the connection between the practical activities carried out and the theory discussed in the Introduction. This can be done by highlighting how the methods of calculating arithmetic mean were applied in the activities and how the results were interpreted.
   • Step by step:
     1. The teacher should briefly review what was discussed in the Introduction, emphasizing the key points.
     2. The teacher should then explain how the methods of calculating arithmetic mean were applied in the practical activities.
     3. Finally, the teacher should highlight the main conclusions that students drew from the activities and how they relate to the theory.

3. Group Discussion 2: (2 - 3 minutes)

   • Description: The teacher should promote a group discussion about the main difficulties encountered by students during the activities. This may include questions about understanding the concept of arithmetic mean, the process of calculating the mean, and interpreting the results.
   • Step by step:
     1. The teacher should ask open-ended questions to the class, such as "What were the biggest challenges you faced during the activities?" or "What do you think you could have done differently to improve your results?".
     2. The teacher should listen attentively to students' responses and provide constructive feedback.
     3. The teacher should conclude the discussion by reinforcing the key points and the main lessons learned.

4. Individual Reflection: (1 minute)

   • Description: To conclude the lesson, the teacher should ask students to silently reflect for a minute on what they have learned. The teacher can ask questions like: "What was the most important concept you learned today?" or "What questions have not been answered yet?".
   • Step by step:
     1. The teacher asks students to close their eyes and reflect silently on the lesson.
     2. After a minute, the teacher asks students to share their reflections, if they wish.
     3. The teacher thanks the students for their participation and ends the lesson.

Conclusion (5 - 7 minutes)

1. Content Summary: The teacher should recap the main points covered during the lesson. This includes the definition of arithmetic mean, the formula to calculate it, how to apply the mean in different situations, and the importance of arithmetic mean in everyday life. The teacher can use practical examples to illustrate each point and reinforce students' understanding. (2 - 3 minutes)

2. Connection between Theory, Practice, and Applications: The teacher should highlight how the lesson connected theory (the concept of arithmetic mean), practice (the activities of calculating the mean), and applications (real-world situations where the mean is used). The teacher can emphasize that the goal of the lesson was not just to learn how to calculate the mean, but also to understand why and how it is used. (1 - 2 minutes)

3. Extra Materials: The teacher can suggest additional materials for students who wish to deepen their understanding of arithmetic mean. This may include math books, online education websites, explanatory videos, math games, and learning apps. The teacher can also suggest homework exercises related to the topic for students to practice what they have learned. (1 minute)

4. Relevance of the Subject: To conclude, the teacher should emphasize the importance of arithmetic mean in everyday life. This can be done by mentioning real examples, such as the average grades in a school, the average prices of products in a supermarket, the average temperatures in a season, among others. The teacher should emphasize that mathematics, and particularly statistics, is a powerful tool for understanding and interpreting the world around us. (1 minute)