Objectives (5 minutes)

1. Understand the concept of circle perimeter: The teacher must ensure that the students understand what the perimeter of a circle is and how it is calculated. This includes defining a circle, the concept of circumference, and how to measure the perimeter.

2. Apply the formula for the perimeter of a circle: Students should be able to apply the correct formula to calculate the perimeter of a circle. This involves knowledge of pi (π) and the radius or diameter of the circle.

3. Solve problems involving the perimeter of a circle: The final objective of the lesson is for students to be able to solve practical problems involving the calculation of the perimeter of a circle. This may include determining the perimeter based on a diagram or solving word problems involving the perimeter of a circle.

Secondary Objectives:

• Develop critical thinking and problem-solving skills: By solving problems involving the perimeter of a circle, students should be encouraged to think critically and develop their problem-solving skills.

• Promote active learning and classroom participation: The teacher must ensure that students are actively involved in the lesson, asking questions, participating in discussions, and solving problems.

Introduction (10 - 15 minutes)

1. Review of previous concepts: The teacher should start the lesson by briefly reviewing the concepts of circle, radius, and diameter, as these will be fundamental to understanding the concept of circle perimeter. He can do this by asking direct questions to the students or by asking them to explain these concepts in their own words.

2. Problem situation 1: The teacher can present a problem situation to arouse the students' interest. For example, he can show a drawing of a circle and ask the students to imagine they are putting a fence around the circle. The challenge would be to calculate the total length of the fence needed.

3. Problem situation 2: Another problem situation that can be presented is the following: 'Imagine you have a round cake and want to decorate the edge with a ribbon. How do you calculate the length of ribbon needed?'

4. Contextualization: The teacher should explain that calculating the perimeter of a circle is a useful skill in many practical situations, such as in construction, architecture, garden design, among others. Additionally, he can mention that the perimeter of a circle is used in many mathematical and scientific formulas.

5. Introduction to the topic: To introduce the topic in an engaging way, the teacher can share some curiosities about the circle and the number pi (π). For example, he can talk about how the number pi is a mathematical constant that appears in many areas of science and nature, or how the circle is one of the most perfect and symmetrical shapes that exist.

Development (20 - 25 minutes)

1. Circle Perimeter Theory (10 minutes):

   • The teacher should start by explaining what the perimeter of a circle is and how it differs from the perimeter of other shapes, such as squares or rectangles.
   • He should emphasize that the perimeter of a circle is the total distance around the circumference.
   • The teacher should introduce the formula for the perimeter of a circle, which is P = 2πr, where P is the perimeter, π is a constant (approximately 3.14), and r is the radius of the circle.
   • He should explain that the radius is the distance from the center of the circle to any point on the circumference.

2. Perimeter Calculation Practice (10 minutes):

   • After explaining the theory, the teacher should show students how to apply the formula for the perimeter of a circle in practical problems.
   • He should start with simple examples, such as calculating the perimeter of a circle with a radius of 5cm.
   • Next, he should move on to more complex problems, such as calculating the perimeter of a circle with a diameter of 10m.
   • The teacher should encourage students to do the calculations in their own notebooks while he does the same on the board, so they can check if their results are correct.

3. Concrete Problem Solving (5 minutes):

   • After the calculation practice, the teacher should present students with problems that involve applying the perimeter of a circle in real situations.
   • For example, he can present a word problem that involves calculating the perimeter of a circle to determine the amount of paint needed to paint the edge of a plate.
   • The teacher should guide students in solving these problems, encouraging them to think critically and apply what they have learned.

4. Discussion and Feedback (5 minutes):

   • After solving the problems, the teacher should promote a brief discussion about what was learned.
   • He should ask students if they have any questions and if they feel confident to solve similar problems in the future.
   • The teacher should provide constructive feedback to students, praising their efforts and correcting any misunderstandings. He should also reinforce the importance of calculating the perimeter of a circle in practical and academic situations.

Return (10 - 15 minutes)

1. Concepts Review (5 minutes):

   • The teacher should start the Return stage by quickly reviewing the main concepts covered in the lesson. He can ask students to explain, in their own words, what they learned about the concept of circle perimeter and how to calculate it.
   • The teacher should reinforce the importance of understanding the formula for the perimeter of a circle and how it is applied in different problems.
   • He should also review the relationship between the radius, the diameter, and the perimeter of the circle, and how the constant pi (π) is used in the perimeter calculation.

2. Connecting Theory with Practice (5 minutes):

   • Next, the teacher should help students make the connection between the theory learned and the practice. For example, he can ask students how they could apply what they learned about the perimeter of a circle in everyday situations or in other disciplines.
   • The teacher can propose a practical problem to be solved together with the class, using the calculation of the circle perimeter. For example, he can ask students to calculate the perimeter of a circular pizza, or the amount of wire needed to make a circle of a certain radius.
   • He should encourage students to ask questions and discuss possible applications of the theory in practice.

3. Individual Reflection (3 minutes):

   • The teacher should give students time to reflect individually on what they learned. He can ask them to write in their notebooks or on a piece of paper the answers to the following questions:
     1. What was the most important concept you learned today?
     2. What questions have not been answered yet?
     3. How can you apply what you learned about the perimeter of a circle in your daily life or in other disciplines?
   • The teacher should remind students that there are no right or wrong answers to these questions, and the idea is for them to reflect honestly on what they learned and on possible doubts or applications of the content.

4. Sharing and Closing (2 minutes):

   • Finally, the teacher can ask some students to share their answers with the class. This can help promote student participation and engagement, as well as provide valuable feedback to the teacher on what was well understood and what still needs to be reinforced.
   • The teacher should end the lesson by reinforcing the importance of what was learned and encouraging students to continue exploring the topic on their own, whether through additional readings, calculation practices, or discussions with peers.

Conclusion (5 - 10 minutes)

1. Summary of Contents (2 minutes): The teacher should give a brief summary of the main points covered during the lesson. He should reaffirm the concept of circle perimeter, the formula to calculate the perimeter (P = 2πr), and the importance of the radius and diameter for the calculation. The teacher can, for example, recap each of these points in a list on the board, or ask students to remember them out loud.

2. Connection between Theory and Practice (2 minutes): The teacher should explain how the lesson connected the theory of calculating the perimeter of a circle with practice. He should mention the calculation exercises performed, as well as the problem situations presented, which helped students understand and apply the concept of circle perimeter. The teacher can also emphasize that calculating the perimeter of a circle is a useful skill in various areas, such as engineering, architecture, science, and mathematics.

3. Additional Materials (2 minutes): The teacher should suggest some additional study materials for students who wish to deepen their knowledge of the perimeter of a circle. These materials may include textbooks, educational websites, explanatory videos, online math games, among others. The teacher should emphasize that self-study is an important part of the learning process and that these resources can be useful for clarifying doubts and reinforcing understanding.

4. Importance of the Subject (2 minutes): To conclude, the teacher should emphasize the importance of the subject covered for everyday life and other disciplines. For example, he can mention that calculating the perimeter of a circle is used in many practical situations, such as in the construction of wheels and tires, in measuring areas of circular lands, in determining distances on maps, among others. The teacher should also highlight that the study of circles and the number pi (π) has implications in various areas of science and technology, such as physics, engineering, computing, astronomy, among others.