Objectives (5 - 10 minutes)

1. Understand the Circulatory System: The teacher should ensure that the students understand the concept of the circulatory system, its main functions, and how it contributes to the overall functioning of the human body.

2. Identify the Components of the Circulatory System: Students should be able to identify and describe each of the components of the circulatory system, including the heart, blood vessels, and blood. They should understand the role of each component and how they work together to ensure the efficient circulation of blood.

3. Learn about blood cells: The teacher should ensure that the students comprehend the crucial role of blood cells in the circulatory system. They should learn about the different types of blood cells, their specific functions, and how they contribute to the overall health and well-being of the human body.

Secondary objectives:

• Stimulate critical thinking: The teacher should encourage students to think critically about the importance of the circulatory system for the overall health of the human body. This can be done through reflective questions and classroom discussions.

• Promote active learning: Students should be encouraged to actively participate in the lesson by asking questions, sharing their opinions, and engaging in hands-on activities related to the topic. This will help improve knowledge retention and understanding of the topic.

Introduction (10 - 15 minutes)

1. Review of previous content: The teacher should begin the lesson by briefly reminding students of the prior knowledge required to understand the topic of the lesson. This may involve a quick review of the human body and its main functions, with an emphasis on the cardiovascular system.

2. Problem situation: To spark students' interest, the teacher could present two problem situations related to the circulatory system. The first could be the question of how blood is able to travel throughout the body, even though it is a liquid, and the second could be about what happens when blood flow is interrupted, such as in cases of strokes.

3. Contextualization: The teacher should contextualize the importance of the circulatory system, explaining how it is essential for human life as it delivers nutrients and oxygen to all the body's cells, while also removing waste products and carbon dioxide. One can highlight how the circulatory system is crucial for physical activities, clear thinking, and even survival.

4. Introduction to the topic: To gain the students' attention, the teacher could share some curiosities or interesting facts about the circulatory system. For example, the fact that, on average, the human heart beats around 100,000 times per day, and that the circulatory system contains around 100,000 km of blood vessels. Another curiosity is the existence of different types of blood cells, each with a specific function, such as carrying oxygen (red blood cells), fighting infections (white blood cells), and helping in blood clotting (platelets).

Development (20 - 25 minutes)

1. Explanation of the Theory (10 - 15 minutes):

   • The teacher should start by explaining what the circulatory system is, how it works, and what its importance is for the human body.
   • Then, they should detail each of the components of the circulatory system: the heart, blood vessels, and blood. To do this, they can use visual schemes, mock-ups, or interactive digital models to demonstrate the structure and function of each component.
   • The teacher should explain how the heart acts as a pump, moving blood through the blood vessels. They should also explain the difference between arteries (which carry blood from the heart to the rest of the body), veins (which carry blood back to the heart), and capillaries (the smallest blood vessels that allow for the exchange of nutrients and waste products between the blood and the body's cells).
   • Regarding blood, the teacher should explain that it is made up of plasma and different types of blood cells: red blood cells, white blood cells, and platelets. They should detail the function of each type of cell and discuss the importance of plasma in blood circulation.
   • Finally, the teacher should explain what blood circulation is and how it occurs in the human body, from the heart to the rest of the body and back to the heart.

2. Practical Activities (5 - 10 minutes):

   • After explaining the theory, the teacher should propose some practical activities to reinforce the students' understanding. One of these could be building a simple model of the circulatory system, using straws to represent blood vessels and cotton balls to represent blood cells. Students would work in groups and, at the end, each group should present their model to the class, explaining the role of each component and how they interact to ensure the efficient circulation of blood.
   • Another practical activity could be carrying out a simple experiment to demonstrate the action of the heart. The teacher could use a balloon and a syringe to simulate the movement of the heart, while students observe the flow of “blood” (represented by colored water) through the “blood vessels” (represented by transparent tubes).
   • The teacher should circulate around the classroom, assisting groups with the activities, clarifying doubts, and encouraging everyone's participation.

3. Discussion and Reflection (5 minutes):

   • At the end of the practical activities, the teacher should promote a class discussion, asking students to share what they learned and what their main difficulties were. This will help to reinforce learning and identify possible gaps in the students' understanding, which can be addressed in future lessons.
   • The teacher should also encourage students to reflect on the importance of the circulatory system for human health and how they can take better care of their own circulatory system, through healthy practices such as a balanced diet and regular physical exercise.

Feedback (10 - 15 minutes)

1. Review of Contents (5 - 7 minutes):

   • The teacher should start the Feedback stage by reviewing the main concepts discussed in class. This can be done through a classroom discussion, where the teacher asks directed questions to students and encourages them to share what they have learned.
   • It is important for the teacher to check that students have been able to understand and explain what the circulatory system is, its components (heart, blood vessels, and blood), blood cells, and blood circulation.
   • The teacher should also review the practical activities carried out, reinforcing the role of each component of the circulatory system and how they work together to ensure the efficient circulation of blood.

2. Connection between Theory, Practice, and Applications (3 - 5 minutes):

   • The teacher should then help students make the connection between the theory learned, the practical activities carried out, and the real applications of the circulatory system.
   • This may involve discussing how the acquired knowledge can be applied to understand and explain everyday phenomena, such as the feeling of warmth after physical exercise (increased blood flow to the skin to dissipate heat) or the cause and effects of cardiovascular diseases (which affect the circulatory system).
   • The teacher should also emphasize the importance of taking care of the circulatory system through healthy habits, such as a balanced diet, regular physical exercise, and maintaining a healthy weight.

3. Reflection on Learning (2 - 3 minutes):

   • Finally, the teacher should propose that students reflect on what they have learned in the lesson. To do this, they can ask questions such as: “What was the most important concept that you learned today?” and “What questions still need to be answered?”.
   • The teacher should allow some time for students to think, and then ask some students to share their answers with the class. This will not only help reinforce learning, but will also allow the teacher to identify possible learning difficulties that can be addressed in future lessons.

Conclusion (5 - 10 minutes)

1. Summary of Contents (2 - 3 minutes):

   • The teacher should start the Conclusion by summarizing the main points discussed in class. This includes a recap of what the circulatory system is, its components (heart, blood vessels, and blood), and the blood cells.
   • The importance of the circulatory system for human health should be highlighted again, reinforcing the main functions of the circulatory system and how they contribute to the overall functioning of the human body.

2. Connection between Theory, Practice, and Applications (1 - 2 minutes):

   • The teacher should reinforce the connection between the theory learned, the practical activities carried out, and the real applications of the circulatory system.
   • One can emphasize how the knowledge acquired in the lesson can be applied to understand and explain everyday phenomena, such as the feeling of warmth after physical exercise and the cause and effects of cardiovascular diseases.

3. Complementary Materials (1 - 2 minutes):

   • The teacher should suggest complementary materials for students who want to deepen their knowledge about the circulatory system. This may include books, scientific articles, educational videos, and reliable websites on the subject.
   • They could also suggest extra activities, such as researching a specific aspect of the circulatory system or carrying out simple experiments at home to demonstrate some of the concepts learned in class.

4. Importance of the Topic (1 - 2 minutes):

   • Finally, the teacher should summarize the importance of the circulatory system for human life.
   • One can highlight how understanding the circulatory system can help people take better care of their health, through healthy practices such as a balanced diet and regular physical exercise.
   • The teacher should also emphasize the relevance of the circulatory system to other areas of knowledge, such as medicine, biology, physical education, among others.