Objectives (5 - 7 minutes)

1. Understand the concept of composition and decomposition of natural numbers less than 100: Students should be able to understand that a number can be formed by joining two or more parts (composition) and that, on the other hand, a number can be divided into its constituent parts (decomposition).

2. Apply the skill of composition and decomposition of numbers: Students should be able to apply this knowledge in solving simple mathematical problems, such as addition and subtraction of two-digit numbers.

3. Develop logical and critical thinking skills: Through the composition and decomposition of numbers, students will be encouraged to think logically and critically, identifying patterns and relationships between numbers. This objective aims to promote mathematical thinking and problem-solving effectively.

Each objective will be clearly communicated to the students at the beginning of the lesson so that they know what is expected of them by the end of the lesson. The teacher will remind them of these objectives throughout the lesson, reinforcing the importance of learning and encouraging active participation.

Introduction (10 - 12 minutes)

1. Recalling previous concepts: The teacher will start the lesson by reminding students about the basic concepts of adding and subtracting single-digit numbers. He may propose some simple problems involving these operations to reinforce students' memory. For example, "How many fingers do we have on two hands? If we take one finger from each hand, how many fingers are left?".

2. Problem Situation: The teacher will present a problem situation to capture the students' attention. He may ask, "If we have 35 candies and give 10 to a friend, how many candies do we have left? And if we then receive 15 more candies from another friend, how many candies will we have?".

3. Contextualization: The teacher will explain that mathematics is very useful in our daily lives, especially for solving problems like this. He can give examples of how addition and subtraction are used in everyday situations, such as shopping, counting objects, sharing sweets with friends, etc.

4. Introducing the topic: The teacher will introduce the topic of the lesson - the composition and decomposition of numbers - in a simple and accessible way. He can say, "Today we are going to learn how to break and join numbers! This will help us solve more complicated math problems in an easier way".

5. Curiosities: To arouse students' interest, the teacher can share some curiosities about numbers. For example, he can say, "Did you know that all numbers less than 100 are made up of just two types of numbers: those ranging from 0 to 9, which we call units, and those ranging from 10 to 90, which we call tens?". Or he can say, "Did you know that the word 'digit' comes from the name of a 9th-century Arab mathematician named Al-Khwarizmi? He was one of the first to use the numbers we use today!".

During the introduction, the teacher should encourage active student participation by asking questions, listening to their answers, and valuing their prior knowledge. Additionally, he should ensure that all students are understanding the concepts presented, using visual and practical examples whenever possible.

Development (20 - 25 minutes)

Activity 1: "Numeric Puzzle"

1. Preparation: The teacher should prepare cards in advance with two-digit numbers (10 to 99), drawings or images representing tens and units (for example, 1 ball to represent 10 and 5 cars to represent 50), and cards with addition and subtraction problems suitable for the students' level.

2. Presentation: The teacher will distribute the cards to the student groups, ensuring that each group has a variety of numbers, drawings, and problems.

3. Execution: The students, in their groups, should combine the number and drawing cards to compose the total number represented on the card (composition). Then, they must "break" the number, separating it into its constituent parts (decomposition). For example, if they have the card with the number 35 and the drawing of 3 tens and 5 units, they must understand that 35 = 30 + 5 and 35 = 3 x 10 + 5.

4. Group Discussion: After all groups have completed the activity, the teacher will facilitate a group discussion, asking each team to share their findings and strategies. The teacher will reinforce the concept of composition and decomposition based on the students' contributions, reminding them that the number 35, for example, can be represented in different ways (35 = 30 + 5, 35 = 20 + 15, 35 = 10 + 25, etc.).

Activity 2: "Breaking Codes"

1. Preparation: The teacher should prepare cards in advance with numerical codes that need to be broken to reveal the original number. For example, the code "2 tens, 5 units, 1 ten" reveals the number 21. The cards should have a variety of difficulty levels, suitable for the students' level.

2. Presentation: The teacher will distribute the cards to the student groups, ensuring that each group has a variety of difficulty levels.

3. Execution: The students, in their groups, must work together to decipher the code and reveal the original number. They must understand that, to decipher the code, they need to decompose the number represented in the code into its constituent parts (tens and units).

4. Group Discussion: After all groups have completed the activity, the teacher will facilitate a group discussion, asking each team to share how they deciphered the code and how they arrived at the original number. The teacher will reinforce the concept of decomposition, reminding them that to decipher the code, it was necessary to "break" the number.

Both activities are playful and allow students to experience the composition and decomposition of numbers in a practical and fun way. Additionally, working in groups allows students to learn from each other, practicing collaboration and communication skills.

Return (10 - 15 minutes)

1. Group Discussion: The teacher will gather all students in a large circle for a group discussion. Each group will have the opportunity to share their findings and solutions. During the discussion, the teacher will encourage students to explain how they arrived at their answers and the strategies they used. He will also ask questions to promote critical thinking and understanding of the concepts. For example, "Why did you choose this strategy to solve the problem?" or "Did you notice any patterns in the numbers you composed and decomposed?".

2. Connection to theory: After the discussion, the teacher will make the connection between the practical activities and the theory. He will reinforce the concept of composition and decomposition of numbers, explaining that this skill allows breaking a number into its constituent parts (units and tens) and joining these parts to form a larger number. The teacher will also emphasize the importance of this skill in mathematics and in daily life, showing examples of how it can be applied in different situations.

3. Individual reflection: To conclude the lesson, the teacher will propose that students reflect individually on what they have learned. He will ask two simple questions to guide students' reflection. The first question will be: "How can you use what you learned today to solve math problems in the future?". The second question will be: "What was the most challenging and the most fun part of today's lesson?".

4. Sharing reflections: After a minute of reflection, the teacher will ask some students to share their answers with the class. He will encourage students to listen attentively to their classmates' answers, reinforcing the importance of respect and appreciation of others' ideas.

This return is crucial to consolidate students' learning, allowing them to apply what they have learned, reflect on the learning process, and share their experiences. Additionally, group discussions and individual reflection promote important skills such as communication, critical thinking, and self-assessment.

Conclusion (5 - 7 minutes)

1. Summary of Contents: The teacher will recap the main points covered in the lesson. He will reinforce the concept of composition and decomposition of natural numbers less than 100, highlighting the importance of this skill for solving more complex math problems. The teacher can use practical and contextualized examples to reinforce learning, such as sharing sweets among friends, counting objects in a collection, among others.

2. Connection between Theory and Practice: The teacher will explain how the activities carried out in the classroom connected theory to practice. He will emphasize that practicing the composition and decomposition of numbers through games allowed students to experience and understand the concept more deeply, making learning more meaningful.

3. Additional Materials: The teacher will suggest extra materials for students who wish to deepen their understanding of the composition and decomposition of numbers. This may include children's books on mathematics, educational online games, or even activities to be done at home with the help of parents. For example, the teacher may suggest reading the book "O Gato de Botas e os Números" by Ana Maria Machado, which addresses the concept in a playful and fun way.

4. Importance of the Subject: Finally, the teacher will emphasize the importance of what was learned for the students' daily lives. He will explain that the composition and decomposition of numbers are fundamental skills for solving everyday problems, such as mental math calculations, sharing objects equally among friends, or calculating change in a purchase. Additionally, the teacher will emphasize that understanding these basic concepts is essential for the development of more advanced mathematical skills in the future.

The conclusion is a crucial step to consolidate students' learning, reinforce the relevance of the content presented, and stimulate continued study outside the classroom. By the end of the lesson, students should have acquired a solid understanding of the composition and decomposition of numbers and be motivated to explore more on the subject.