Objectives (5 - 7 minutes)

1. Understand the concept of solubility and solutions: Students should be able to define solubility and describe what happens at a molecular level when a substance dissolves in another. They should also understand what a solution is and how it differs from a mixture.

2. Identify factors that influence solubility: Students should be able to identify and explain how temperature, pressure, and the nature of substances affect solubility.

3. Calculate the concentration of a solution: Students should be able to perform calculations to determine the concentration of a solution, whether in mass (g/L), in amount of substance (mol/L), or in number of particles (particles/mL).

Secondary objectives:

• Apply the acquired knowledge in practical situations: Students should be able to apply what they have learned about solubility and concentration of solutions in practical situations, such as preparing a solution with a specific concentration.

Introduction (10 - 15 minutes)

1. Review of previous content: The teacher should start the lesson by briefly reviewing the concepts of mixtures, pure substances, and states of matter, as these concepts are fundamental to understanding the topic of solubility and solutions. This review can be done interactively, involving students in a discussion about practical examples of these concepts.

2. Problem situations: The teacher should present two situations that will arouse students' interest and prepare them for the content to be covered. The situations can be:

   • Situation 1: "Why does sugar dissolve easily in water, but not in gasoline?"
   • Situation 2: "How could we prepare a solution of table salt with a specific concentration, for example, 100 g of salt in 1 liter of water?"

3. Contextualization: The teacher should explain the importance of studying solubility and solutions, using practical examples from everyday life. Some examples may include the importance of solubility in food and beverage preparation, stain removal, and dissolution of medications.

4. Introduction to the topic: The teacher should introduce the topic of solubility in an engaging way, using related curiosities or stories. Some suggestions are:

   • Curiosity 1: "Did you know that the salt we use to season food is an example of a solution? It is composed of sodium and chlorine ions that separate in water, forming a solution."
   • Curiosity 2: "Some substances have such low solubility that they are considered practically insoluble. An example is gold, which is so slightly soluble in water that it would take a 50-meter deep lake to dissolve just one gold coin."

By the end of this stage, students should be curious and motivated to learn more about solubility and solutions.

Development (20 - 25 minutes)

1. "Solution Factory" Activity: The teacher should divide the classroom into groups of 4-5 students. Each group will receive a "laboratory kit" containing:

   • Several containers of different sizes (cups, beakers, flasks, etc.),
   • Different types of substances (salt, sugar, coffee powder, flour, etc.),
   • Room temperature water,
   • A thermometer,
   • A stopwatch.

   The objective of the activity is for the groups to create different solutions, observe the solubility of the substances, and record their observations. They should try to answer the following questions:

   • Question 1: "Which substances dissolve completely in water and which do not dissolve?"
   • Question 2: "Does the water temperature affect the solubility of substances? How?"
   • Question 3: "If we add more of a substance in the same volume of water, does the solution's concentration increase? How could we measure this concentration?"

   The teacher should circulate around the room, guiding the groups, clarifying doubts, and encouraging discussion. At the end of the activity, each group should present their observations and conclusions to the class.

2. "Solutions in Everyday Life" Activity: After the "Solution Factory" activity, the groups should discuss and list situations from everyday life that involve solutions. They should identify the substances that dissolve, the nature of the solvent, the concentration of the solution, etc. Some examples may include:

   • Preparation of juices, soft drinks, and teas,
   • Stain removal with cleaning products,
   • Use of medications and supplements,
   • Preparation of foods such as pasta, rice, beans, etc.

   Each group should choose one of the situations and prepare a presentation for the class, explaining how solubility and substance concentration are important in that situation.

3. Group Discussion: To conclude the Development stage, the teacher should promote a group discussion. Students should share the solutions they found for the problem situations presented at the beginning of the lesson and discuss the different approaches. The teacher should reinforce the concepts learned, correct possible misconceptions, and clarify doubts. This is an opportunity for students to apply the acquired knowledge and develop critical thinking and teamwork skills.

Return (8 - 10 minutes)

1. Group Discussion: The teacher should gather all students for a group discussion. Each group should share their solutions and conclusions from the "Solution Factory" and "Solutions in Everyday Life" activities. This discussion should be guided by the teacher and focus on how the activities relate to the theory of solubility and solutions. The teacher should emphasize key concepts and correct possible misconceptions. (3 - 4 minutes)

2. Connection with theory: The teacher should explain how the practical activities carried out connect with the theory presented in the Introduction of the lesson. They can use examples from the students' activities to illustrate theoretical concepts and reinforce the importance of understanding solubility and solutions for explaining and predicting a variety of chemical phenomena. (2 - 3 minutes)

3. Individual Reflection: The teacher should propose a moment of individual reflection. Students should think for a minute about the answers to the following questions:

   1. "What was the most important concept learned today?"
   2. "What questions have not been answered yet?"

   After this minute of reflection, students should be encouraged to share their answers with the class. The teacher should listen carefully to the students' answers, as they can provide valuable feedback on the effectiveness of the lesson and areas that may need reinforcement in future classes. (1 - 2 minutes)

4. Lesson Closure: To conclude the lesson, the teacher should recap the main points discussed and reinforce the most important concepts. They should also inform students about the next steps in studying solubility and solutions. This may include reading a chapter from the textbook, doing homework exercises, or preparing for a laboratory class. (1 minute)

Conclusion (5 - 7 minutes)

1. Lesson Summary: The teacher should start the Conclusion by recapping the main points discussed during the lesson. This includes the concept of solubility, the factors that influence it (temperature, pressure, and nature of substances), and how to calculate the concentration of a solution. The teacher should check if all students understood these concepts and clarify any remaining doubts. (2 - 3 minutes)

2. Connection between Theory, Practice, and Applications: The teacher should highlight how the lesson connected the theory of solubility and solutions with practice and applications in everyday life. This can be done by recalling the "Solution Factory" and "Solutions in Everyday Life" activities and how they helped illustrate and apply theoretical concepts. The teacher should emphasize the importance of understanding the solubility and concentration of substances to explain and predict a variety of chemical phenomena. (1 - 2 minutes)

3. Additional Materials: The teacher should suggest additional study materials for students to deepen their understanding of solubility and solutions. These may include specific chapters from the textbook, online videos, interactive simulations, additional practical activities, among others. The teacher should emphasize that reviewing these materials will be useful for understanding future related topics. (1 minute)

4. Importance of the Subject: To conclude, the teacher should reinforce the importance of studying solubility and solutions. They should explain how these concepts are fundamental to many aspects of everyday life, including food and beverage preparation, cleaning, medicine, among others. The teacher may also mention how understanding these concepts is relevant to the study and practice of other disciplines, such as biology and engineering. (1 minute)