Objectives (5 - 10 minutes)

1. Introduce the concept of angles and their importance in geometry.

   • Explain that angles are formed by the union of two half-lines from a common point, known as the vertex.
   • Show examples of angles in everyday objects and figures.

2. Teach the classification of angles as: right, obtuse, and acute.

   • Define each type of angle and its respective characteristics.
   • Propose practical activities for students to identify and classify angles.

3. Develop students' ability to identify and classify angles through problem-solving situations.

   • Present problems that involve the identification and classification of angles.
   • Guide students to solve the problems autonomously, encouraging critical thinking and problem-solving.

Secondary Objectives:

• Stimulate logical thinking and observational skills of students through the analysis of figures and objects containing angles.
• Encourage teamwork and exchange of ideas among students during problem-solving related to angles.
• Promote the connection between mathematics and the real world, showing students the presence and importance of angles in various everyday situations.

Introduction (10 - 15 minutes)

1. Review of previous contents:

   • The teacher should start the class with a brief review of the contents that are prerequisites for understanding the current topic, such as the notion of point, line, half-line, and plane, as well as basic concepts of geometry. This can be done interactively, through questions and answers, to assess students' prior knowledge.

2. Initial problem-solving situations:

   • The teacher can present two initial situations that arouse students' curiosity and lead them to realize the importance of angles. For example:
     • Situation 1: 'Imagine you are building a building. How could you ensure that the walls are perfectly straight and forming 90-degree angles?'
     • Situation 2: 'Have you noticed that the clock hands form different angles every hour? How could we classify these angles?'

3. Contextualization:

   • The teacher should then contextualize the importance of angles, showing how they are present in our daily lives, from the architecture of buildings and bridges to reading time on the clock. This can be done through images and practical examples, making the subject more concrete and relevant to students.

4. Introduction to the topic:

   • To introduce the topic of angles, the teacher can tell the story of how the ancient Egyptians used angles to build the pyramids, or how astronomers use angles to measure the distance between stars. These historical and scientific curiosities can help spark students' interest in the subject.

5. Engage students' attention:

   • Finally, the teacher can propose a challenge: 'Let's try to draw a 90-degree angle without using a set square?' This practical activity will grab students' attention and prepare them for the Development of the content.

Development (20 - 25 minutes)

1. Practical Activity #1: 'Measuring angles with the clock'

   • Necessary material: Clocks with hands (or printed clock images).
   • Divide the class into groups of 3 to 4 students.
   • Each group receives a clock with hands (or an image of a printed clock).
   • The objective of the activity is for students to observe the clock and identify different angles formed by the hands. They should record the measurement of each angle, identify if it is acute, right, or obtuse, and justify their classification.
   • The teacher circulates around the room, offering support when necessary, and encouraging students to think critically and discuss their observations in groups.
   • After the activity, each group should briefly present their findings to the class.

2. Practical Activity #2: 'Building angles on paper'

   • Necessary material: Paper, pencils, and ruler.
   • Each group receives a sheet of paper, a pencil, and a ruler.
   • The teacher gives instructions for students to draw and classify angles on the paper. Instructions may include: 'Draw a right angle', 'Draw an acute angle', 'Draw an obtuse angle', etc.
   • Students should follow the instructions and draw the angles. They should then measure the angles with the ruler and verify if their classifications were correct.
   • The teacher circulates around the room, offering support when necessary, and encouraging students to discuss their strategies and results in groups.
   • At the end of the activity, each group should have a sheet of paper with several angles drawn and classified.

3. Application Activity #3: 'Angle hunt at school'

   • Necessary material: Cell phones or tablets with a camera (optional), paper, and pen.
   • The teacher suggests that students leave the classroom and 'hunt' for angles around the school. They can observe angles formed by walls, tables, chairs, doors, windows, etc.
   • Students should record the angles they find, indicating if they are acute, right, or obtuse. If possible, they can take photos of the angles with their cell phones or tablets.
   • Back in the classroom, students should share their observations and discuss their classifications in groups. The teacher can then consolidate learning by correcting any misunderstandings and reinforcing the concepts learned.

These practical and playful activities are designed to actively engage students in the learning process, promoting understanding and retention of the content. Additionally, they encourage collaboration, communication, and critical thinking, essential skills for success in mathematics and other disciplines.

Return (10 - 15 minutes)

1. Group discussion (5 - 7 minutes):

   • The teacher should gather all students and promote a group discussion about the activities carried out. Each group should share their findings and conclusions, and other students should be encouraged to ask questions and make comments.
   • During the discussion, the teacher should make connections between the activities and the theoretical content, reinforcing the concepts of angles and their classification.
   • The teacher should also take the opportunity to correct any misunderstandings and reinforce the most important points of the content.

2. Learning verification (3 - 5 minutes):

   • The teacher should propose a quick verification of learning, through oral or written questions. For example, the teacher can ask: 'What is a right angle?' or 'How would you classify a 120-degree angle?'.
   • The objective of this stage is to verify if students understood the main concepts and can apply them in different situations. If there are difficulties, the teacher should reexplain the content and propose new reinforcement activities.

3. Individual reflection (2 - 3 minutes):

   • To conclude the class, the teacher should propose that students reflect individually 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?'.
   • Students should have a minute to think about their answers. Then, those who wish can share their reflections with the class. The teacher should value all contributions and clarify any remaining doubts.
   • This reflection stage is important to consolidate learning and stimulate metacognition, that is, students' ability to reflect on their own learning process.

4. Teacher feedback (1 minute):

   • At the end of the class, the teacher should provide general feedback on the class's performance, praising everyone's effort and participation, and highlighting the group's strengths.
   • The teacher should also give a brief preview of what will be covered in the next class, so that students can prepare and continue studying the topic.
   • This feedback is important to motivate students and maintain interest in the subject.

Conclusion (5 - 7 minutes)

1. Content recapitulation (2 - 3 minutes):

   • The teacher should recapitulate the main points covered in the class, reinforcing the definition of angle and the classification of angles as: right, obtuse, and acute.
   • During the recapitulation, the teacher can use diagrams or drawings on the board to illustrate the concepts and make them more visual and understandable.
   • The teacher should also review the practical activities carried out, highlighting the discoveries and conclusions of the students, and reinforcing the concepts that were applied.

2. Connection between theory, practice, and applications (1 - 2 minutes):

   • The teacher should explain how the class connected theory (the concepts of angle and its classification) with practice (the activities of observing and drawing angles) and applications (identifying angles on the clock and at school).
   • The teacher can emphasize how understanding and the ability to work with angles are important not only for mathematics but also for many other areas of knowledge and everyday life, such as physics, engineering, architecture, navigation, etc.

3. Supplementary materials (1 - 2 minutes):

   • The teacher should suggest complementary study materials for students to deepen their understanding of angles. These materials may include math books, educational websites, explanatory videos, games, and online activities, among others.
   • The teacher can also suggest that students continue to observe and analyze angles in their everyday environment, and record their discoveries and reflections in a math journal.
   • The suggestion of these complementary materials and activities can help consolidate learning and motivate students to continue studying the topic on their own.

4. Importance of the subject (1 minute):

   • To conclude the class, the teacher should emphasize the importance of angles for everyday life and the world of work. For example, the teacher can mention that angles are used in building construction, computer game programming, time and distance measurement, among many other applications.
   • The teacher can also emphasize that the study of angles helps develop important skills, such as observation ability, critical analysis, logical reasoning, and problem-solving, which are useful in many aspects of life.