Objectives (5 minutes)

1. Understand and identify flat shapes - Students should be able to recognize and identify different flat shapes, such as squares, rectangles, triangles, and circles. They should understand that these shapes are two-dimensional and exist only on a flat surface.

2. Count sides and vertices of the shapes - Students should learn to count the number of sides and vertices of each shape. They should understand that the sides are the lines that make up the shape, and the vertices are the points where these lines meet.

3. Relate theory and practice - Through practical activities, students should be able to apply what they have learned about flat shapes, sides, and vertices. They should be able to identify the shapes in real situations and count their sides and vertices.

The objectives should be explained clearly and simply, so that students understand what is expected of them by the end of the lesson. The teacher can use visual examples and everyday situations to make the explanation more concrete and understandable.

Introduction (10 - 15 minutes)

1. Review of previous concepts - The teacher should start the lesson by reminding students of what they have learned in previous classes. Questions like: "Who remembers what a straight line is?" and "How many straight lines are needed to form a triangle?" can be asked. This will help prepare the ground for the introduction of the new topic.

2. Problem situations - The teacher should propose two problem situations for the students:

   • "Imagine you have a box of colored pencils. How would you describe the shape of the box? What are the characteristics of the box that we can describe mathematically?"

   • "Now, imagine you have a round pizza. How would you describe the shape of the pizza? What are the characteristics of the pizza that we can describe mathematically?"

3. Contextualization of the topic's importance - The teacher should explain to the students that learning about flat shapes, sides, and vertices is important because these concepts are used in many everyday situations. For example, when building a house, an architect needs to know about the different types of flat shapes in order to draw the house plans. Or, when playing a board game, it is necessary to count the sides and vertices of the pieces in order to play correctly.

4. Introduction of the topic - The teacher should then introduce the topic of the lesson, explaining that they will learn about different flat shapes, such as squares, rectangles, triangles, and circles. The teacher can use real figures and objects to exemplify each shape and explain the definition of sides and vertices.

5. Curiosities - To spark students' interest, the teacher can share some curiosities about the topic:

   • "Did you know that the triangle is the simplest and most basic figure in geometry? All other figures, such as squares and rectangles, can be made from triangles."

   • "And did you know that the circle is the only figure that has no sides or vertices? It is formed by a continuous curve with no beginning or end."

At the end of the introduction, students should have a clear idea of what will be learned in the lesson and why it is important. They should also be enthusiastic and motivated to participate in the practical activities that will follow.

Development (20 - 25 minutes)

Activity 1: Building Flat Shapes with Strings

1. Materials needed - Strings of different lengths and colors, cardboards, scissors, tape, colored markers.

2. Teacher's preparation - Before the lesson, the teacher should cut strings of different lengths to represent the sides of the flat shapes. Cardboards should also be cut into the shape of a square, rectangle, triangle, and circle.

3. Activity step by step:

   • Step 1: The teacher should present a flat shape and explain its shape, sides, and vertices. For example, they can start with a square. They should show the figure on the cardboard and count its sides and vertices together with the students.

   • Step 2: Next, the teacher should take a string and show how it is possible to use the string to trace the shape of the square on the floor or table. Students should observe and count the sides and vertices.

   • Step 3: The teacher should then distribute a string to each group of students and ask them to try to form a square on the floor or table. The teacher should move around the groups to guide and assist, if necessary.

   • Step 4: After everyone has had the opportunity to build the square, the teacher should repeat the process with the other shapes: rectangle, triangle, and circle. Always showing the figure on the cardboard, tracing it with the string, and counting the sides and vertices.

4. Discussion of results: At the end of the activity, the teacher should gather all students in a large circle and ask each group to present the flat shape they built, describe its sides and vertices, and count how many there are. The teacher should correct any mistakes and reinforce the correct concepts.

Activity 2: Memory Game of Flat Shapes

1. Materials needed - Cards with drawings of flat shapes (square, rectangle, triangle, and circle) and their respective names.

2. Teacher's preparation - Before the lesson, the teacher should prepare the cards, drawing the flat shapes and writing their names on cardboards. At least two copies of each shape should be made.

3. Activity step by step:

   • Step 1: The teacher should shuffle the cards well and divide the students into groups of 3 or 4.

   • Step 2: Each group should take a set of cards and shuffle them again. Then, they should place the cards face down, so that they cannot see the drawings or names.

   • Step 3: One student from each group should then turn over two cards. If the cards form a shape and its corresponding name, the student should keep the cards and continue playing. If not, the cards should be turned over again, and the next student in the team plays.

   • Step 4: The game continues until all pairs have been found. The group with the most pairs at the end is the winner.

4. Discussion of results: After the game ends, the teacher should gather all students in a large circle and ask each group to show the pairs they found. The teacher should then reinforce the concepts of each shape and their respective names, as well as the number of sides and vertices of each one.

Both activities are interactive and playful, allowing students to explore the concepts of flat shapes, sides, and vertices in a practical and fun way. The teacher should monitor the activities, offer support when necessary, and ensure that all students are engaged and understanding the concepts.

Feedback (10 - 15 minutes)

1. Group Discussion - The teacher should gather all students in a large circle and promote a discussion about the solutions found by each group in the practical activities. The teacher should ask questions like: "Which shapes were you able to form with the string?" and "How many sides and vertices did each shape have?" This discussion will allow students to share their discoveries, correct any mistakes, and reinforce the concepts learned.

2. Connection with Theory - After the discussion, the teacher should review the theoretical concepts presented at the beginning of the lesson and relate them to the practical activities. It should be highlighted how building the shapes with strings and playing the memory game helped to better understand flat shapes, sides, and vertices. The teacher can ask questions like: "How did the activity with the string help understand what the sides and vertices of a shape are?" and "How did the memory game help remember the names and characteristics of each shape?"

3. Reflection on Learning - The teacher should propose that students reflect on what they learned in the lesson. For this, two simple questions can be asked:

   • "Which shape did you enjoy building with the string the most and why?"
   • "What was the most challenging part of the memory game and why?"

   The teacher should give each student the opportunity to share their answers. This reflection will help students consolidate what they have learned and identify possible difficulties that still need to be overcome.

4. Teacher's Feedback - To end the lesson, the teacher should give an overall feedback on the class performance. Efforts and participation of all students should be praised, the well-understood concepts should be reinforced, and which aspects still need more practice should be pointed out. The teacher can say things like: "You all did a great job building the shapes with the string. Now everyone knows how to count the sides and vertices of a square, rectangle, triangle, and circle!" and "In the memory game, I saw that some of you still have a bit of difficulty remembering the names and characteristics of each shape. Let's keep practicing to make it easier!"

Feedback is a crucial stage to ensure that students have understood the concepts presented and are progressing in their learning. The teacher should conduct this stage with a positive, encouraging, and receptive attitude, valuing the students' efforts and encouraging them to continue learning.

Conclusion (5 - 10 minutes)

1. Summary of Concepts - The teacher should start the conclusion by summarizing the main concepts covered in the lesson. It should be reminded what flat shapes, sides, and vertices are, and the number of sides and vertices of each flat shape studied (square, rectangle, triangle, and circle) should be counted. The teacher can use the shapes built with strings and the memory game cards to illustrate the concepts.

2. Connection between Theory and Practice - Next, the teacher should explain how the lesson connected theory and practice. It should be highlighted how the practical activities allowed students to explore the concepts of flat shapes, sides, and vertices in a concrete and meaningful way. The teacher can say: "Today, we learned about flat shapes, sides, and vertices. We not only talked about it, but also built the shapes with strings and played a game to remember the names and characteristics of each shape. This helped us better understand these concepts."

3. Extra Materials - The teacher can then suggest extra materials for students who wish to deepen their knowledge on the subject. Illustrated math books for children, educational websites with games and interactive activities on flat shapes, and online videos that explain the subject in a simple and fun way can be recommended.

4. Importance of the Subject - Finally, the teacher should emphasize the importance of what was learned. It should be explained that the ability to recognize and count the sides and vertices of flat shapes is fundamental for geometry, which is an essential part of mathematics. Additionally, it should be highlighted that geometry is used in many everyday situations, from building buildings and houses to organizing objects on a shelf. The teacher can say: "Now that we know how to recognize and count the sides and vertices of flat shapes, we can use this knowledge to better understand the world around us. For example, when we see a building, we can recognize that it is made up of many flat shapes, such as squares and rectangles. This helps us understand how the building was constructed and how it stands firm."

The conclusion is an important stage to consolidate learning and motivate students to continue exploring the subject outside the classroom. The teacher should conduct this stage in a clear, engaging, and positive manner, ensuring that all students have understood the concepts presented and feel encouraged to continue learning.