Objectives (5 - 7 minutes)

1. Understand the structure of the circulatory system: The teacher should teach students about the main parts of the circulatory system, including the heart, veins, and arteries. Students should be able to identify these structures and understand their role in the human body.

2. Understand how the circulatory system works: The teacher should explain to students how the circulatory system works, explaining how the heart pumps blood and how veins and arteries transport blood throughout the body. Students should understand the importance of the circulatory system for maintaining life.

3. Recognize the importance of maintaining a healthy circulatory system: The teacher should discuss with students the importance of maintaining a healthy circulatory system, emphasizing healthy practices such as regular physical activity and a balanced diet. Students should be able to explain how these practices can help maintain the circulatory system functioning properly.

Introduction (8 - 10 minutes)

1. Recalling previous concepts: The teacher should start the lesson by reminding students about the human body and its main parts, such as the head, limbs, trunk, etc. This is important so that students can connect the new content with what they have learned before. The teacher can do this through a question-and-answer game or through images and drawings.

2. Problem situations: The teacher can present two problem situations to arouse students' curiosity and introduce the lesson's theme. For example, the teacher can ask: 'Have you ever wondered how blood reaches our fingers when we shake someone's hand?' or 'Have you noticed that when we run or play a lot, our heart beats faster? Why is that?' These simple questions can lead students to think about the circulatory system and how it works.

3. Contextualization: The teacher should explain that the circulatory system is like a network of roads inside our body, carrying blood and nutrients to all parts of our body. He can use everyday examples, such as the delivery of goods by a truck, to illustrate how the circulatory system works. The teacher can also mention that, just as we need to take care of our roads so that they are always in good condition, we also need to take care of our circulatory system so that it functions correctly.

4. Capturing students' attention: To arouse students' interest, the teacher can share curiosities about the circulatory system. For example, he can say that if all our veins, arteries, and capillaries were placed in a straight line, they could go around the Earth several times. Or that the heart beats about 100,000 times a day. Additionally, the teacher can show images or models of the circulatory system so that students can better visualize what they are learning.

Development (20 - 25 minutes)

The teacher should choose one of the practical activities proposed below for the classroom. The goal of these activities is to reinforce the theoretical content presented in the introduction stage, allowing students to understand in a playful and interactive way how the circulatory system works.

1. 'Path of Blood': For this activity, the teacher will need colored cords (red for arteries, blue for veins) and adhesive tape. Initially, students will be divided into groups. Then, each group should draw a sketch of a human body on the floor (with the help of the teacher). The teacher will then mark starting points (heart) and endpoints (toes) on each sketch. Each group will receive a quantity of cords and should 'assemble' the circulatory system, fixing the arteries and veins on the body sketch. During the activity, the teacher can reinforce concepts and explain the function of each part of the circulatory system. At the end, each group should explain what they did and why.

2. 'The Racing Heart': In this activity, the teacher will need stopwatches and can use a large area of the classroom or schoolyard. Students will be divided into groups. Each group will represent an organ of the human body (heart, lungs, muscles, brain, etc.). The teacher will explain that each organ needs blood to function. Students will be instructed to 'pump' blood (symbolized by paper balls) through a certain route (symbolizing arteries and veins) as quickly as possible, using a spoon as a 'pump'. At the end, the group that transports all the paper balls first, without dropping any, will be the winner. The teacher can correlate physical effort with the need for more blood, explaining why the heart beats faster during physical activity.

3. 'Circulator Game': For this activity, the teacher will need to make pieces representing the components of the circulatory system (heart, veins, arteries, capillaries). Students will be divided into groups, and each group will receive a set of these pieces. The teacher will explain that the players are 'red blood cells' and must follow the correct path within the circulatory system. The heart (a student from the group) will launch the 'red blood cells' (small paper balls) on the board (representing the human body), and the other students, representing veins, arteries, and capillaries, must move their pieces to transport the 'red blood cells' around the board. The group that manages to make the most 'red blood cells' follow the correct path to the end of the game wins. During the activity, the teacher can reinforce the theoretical content, explaining the function of each part of the circulatory system.

After conducting one of the practical activities, the teacher should set aside time for students to discuss what they have learned, clarify their doubts, and share their experiences. This is important for the learning consolidation process. The teacher should guide this discussion, reinforcing the main points addressed and correcting any misunderstandings.

Return (10 - 12 minutes)

1. Group Discussion: The teacher should promote a group discussion with all students about the solutions they found during the practical activities. Each group will have the opportunity to share their findings, explaining how they assembled the circulatory system (or how they 'pumped' the blood, in the case of the second activity) and why. The teacher can ask questions to stimulate students' reflection, such as: 'Why do you think the artery is represented by a red cord?' or 'Why do you think the heart beats faster when we move a lot?' The goal is to ensure that students understand how the circulatory system works and the importance of keeping it healthy.

2. Connection with Theory: After the group discussion, the teacher should connect the practical activities with the theory presented at the beginning of the lesson. He can reinforce the concepts, explaining again the role of the heart, veins, and arteries in the circulatory system and how they work together to keep the human body healthy. Additionally, the teacher can revisit the curiosities presented in the introduction, relating them to the content learned. For example, he can ask: 'Remember when I said that if all our veins, arteries, and capillaries were placed in a straight line, they could go around the Earth several times? Now do you understand why?'.

3. Final Reflection: To end the lesson, the teacher should propose that students reflect for a minute on what they have learned. He can ask two simple questions to guide students' reflection: 'What was the most interesting part of today's lesson and why?' and 'What can you do to keep your circulatory system healthy?'. After the reflection, the teacher can ask some students to share their answers with the class, promoting the exchange of ideas and respect for classmates' opinions.

4. Teacher's Evaluation: Throughout the return, the teacher should carefully observe students' responses and interactions. This will allow him to assess students' understanding of the subject and identify any difficulties. The teacher can take note of these observations to guide the preparation of future lessons and the planning of reinforcement activities, if necessary.

Conclusion (5 - 7 minutes)

1. Summary of Key Points: The teacher should end the lesson by summarizing the key points covered during the lesson. He can remind students about the parts of the circulatory system (heart, veins, and arteries), briefly explain how they work together to keep the human body healthy, and highlight the importance of maintaining a healthy circulatory system. The teacher can use images or drawings to illustrate these points and facilitate students' understanding.

2. Connection between Theory, Practice, and Applications: The teacher should explain how the lesson connected theory (learned in the introduction) with practice (performed during the activities) and with applications (discussed during the return). He can highlight how the practical activities helped illustrate and consolidate the theoretical concepts and how the group discussions allowed students to understand the relevance of the circulatory system for the functioning of the human body.

3. Extra Materials: The teacher can suggest extra materials for students who wish to deepen their knowledge of the circulatory system. This may include children's books about the human body, educational websites with interactive games and explanatory videos, and even visits to science museums or physical education classes, which can address the subject in different and complementary ways.

4. Importance of the Subject: Finally, the teacher should emphasize the importance of the subject studied for students' daily lives. He can explain that the circulatory system is essential for our health and well-being, allowing oxygen and nutrients to reach all parts of our body. Additionally, the teacher can emphasize that by understanding how our body works, we can make more conscious decisions about our health, such as the importance of exercising and eating well.

5. Lesson Closure: The teacher should end the lesson by thanking everyone for their participation and encouraging students to continue exploring and learning about the wonderful world of science. He can say: 'Remember, my dear scientists, that discovery is the key to knowledge. Stay curious, ask questions, and seek answers. See you in the next lesson!'.