Objectives (5 - 7 minutes)

1. Understand the definition and characteristics of vertebrate and invertebrate animals.
2. Identify the main differences between these two groups of animals.
3. Analyze examples of animals belonging to each group and classify them correctly.

Secondary Objectives:

1. Develop research skills and autonomous study when searching for information about different types of animals.
2. Stimulate critical thinking by comparing and contrasting the characteristics of vertebrate and invertebrate animals.
3. Deepen students' understanding of the diversity of animal life and the importance of classification.

The teacher should start the lesson by presenting the Objectives and explaining the importance of each one. This will help students understand what is expected of them during the lesson and how the acquired knowledge will be applied.

Introduction (10 - 15 minutes)

1. Review of previous content: The teacher should start the lesson by reviewing the basic concepts of biological classification, especially the classification levels, such as kingdom, phylum, class, order, family, genus, and species. This review is essential for students to understand the classification of animals that will be addressed in the lesson. Additionally, it may be interesting to review the general characteristics of living beings.

2. Problem situations: The teacher can present two situations that arouse students' interest in the topic. For example, he/she can ask: 'Why do humans have a spine and worms do not?' or 'How do insects survive without an internal skeleton like ours?'. These questions will serve as a starting point for the theoretical Introduction to the topic.

3. Contextualization: The teacher should explain the importance of studying vertebrate and invertebrate animals for understanding biodiversity and biological evolution. Additionally, he/she can highlight how knowledge about these animals is applied in different areas, such as medicine (in the study of diseases that affect vertebrates) and agriculture (in the control of invertebrate pests, for example).

4. Introduction to the topic: To arouse students' curiosity, the teacher can share curiosities about vertebrate and invertebrate animals. For example, he/she can talk about the existence of highly intelligent invertebrates, such as squids, or about the diversity of vertebrates, which includes everything from microscopic fish to huge whales. Another interesting curiosity is the fact that vertebrates and invertebrates have a common ancestor, but that over evolution these groups became increasingly distinct.

Development (20 - 25 minutes)

1. Theory: Characteristics of vertebrates and invertebrates: The teacher should start the theoretical part of the lesson by explaining the main characteristics that distinguish vertebrate animals from invertebrates. (10 - 12 minutes)

   1.1. Vertebrate Animals: The teacher should explain that vertebrate animals have a spine, which is a bony structure that protects the spinal cord. Additionally, they have a skull, which protects the brain, and an internal skeleton, composed of bones and cartilage. The teacher should emphasize that vertebrate animals are the only ones that have these characteristics.

   1.2. Invertebrate Animals: The teacher should explain that invertebrate animals do not have a spine, skull, or internal skeleton. Instead, they have a great diversity of support structures, such as exoskeletons (as in insects), shells (as in mollusks), or hydrostatic skeletons (as in jellyfish). The teacher should emphasize that most animals on the planet are invertebrates.

2. Theory: Main animal groups: The teacher should present the main animal groups, dividing them into vertebrates and invertebrates. (5 - 7 minutes)

   2.1. Vertebrate Animals: The teacher should explain that vertebrate animals are divided into five main groups: fish, amphibians, reptiles, birds, and mammals. The teacher should briefly describe the main characteristics of each group and mention some examples of animals belonging to each of them.

   2.2. Invertebrate Animals: The teacher should explain that invertebrate animals are divided into many groups, some of which are: sponges, cnidarians (such as jellyfish), worms (such as earthworms), mollusks (such as snails), arthropods (such as insects and crustaceans), echinoderms (such as starfish), and chordates (such as lancelets). The teacher should briefly describe the main characteristics of each group and mention some examples of animals belonging to each of them.

3. Practice: Animal classification: The teacher should propose an activity in which students, in groups, classify a list of animals as vertebrates or invertebrates. (5 - 6 minutes)

   3.1. The teacher should provide students with a list of animals (for example: snake, eagle, earthworm, starfish, mosquito, squid, etc.) and ask them, in groups, to classify each animal as vertebrate or invertebrate.

   3.2. The teacher should walk around the room, assisting groups that have difficulties and clarifying doubts.

4. Discussion: Importance of classification: The teacher should conclude the theoretical part of the lesson by discussing the importance of animal classification. (2 - 3 minutes)

   4.1. The teacher should explain that animal classification is fundamental for biology, as it allows us to understand the diversity of life on Earth and recognize patterns of similarity and difference among living beings.

   4.2. The teacher should emphasize that classification is also useful in many other areas, such as medicine (for the study of diseases that affect vertebrates), agriculture (for the control of invertebrate pests), biodiversity conservation, among others.

Return (8 - 10 minutes)

1. Group discussion (3 - 4 minutes): The teacher should organize a group discussion with the participation of all students. Each group will have up to 2 minutes to share their answers and conclusions about the animal classification activity. The teacher should encourage students to explain the reasoning they used to classify the animals and to discuss possible difficulties or doubts that arose during the activity.

2. Connection with theory (2 - 3 minutes): After the discussion, the teacher should make the connection between the practical activity carried out and the theory presented. For example, the teacher can ask students how they used the animal characteristics to classify them and how these characteristics relate to the differences between vertebrate and invertebrate animals. The goal of this stage is to reinforce the acquired knowledge and help students consolidate what they have learned.

3. Individual reflection (2 - 3 minutes): Finally, the teacher should propose that students reflect individually on what they learned in the lesson. The teacher can ask the following questions:

   3.1. 'What was the most important concept you learned today?' 3.2. 'What questions have not been answered yet?' 3.3. 'How does what you learned today relate to the world around you?'

   The teacher should give students a minute to reflect on these questions. Then, some students may be invited to share their answers with the class. This stage is important so that students can internalize the acquired knowledge and so that the teacher can assess the effectiveness of the lesson.

The teacher should end the lesson by emphasizing the importance of studying vertebrate and invertebrate animals for understanding biodiversity and biological evolution, and for applying biological knowledge in various areas. Additionally, he/she should reinforce that the classification of living beings is a fundamental tool for biology and that the ability to classify and categorize is essential for scientific thinking.