Objectives (5 - 7 minutes)

1. Understand the concept of chemical solutions and how they are formed from chemical reactions:

   • Students must understand that chemical solutions are formed when two or more substances mix and form a new substance.
   • They should be able to identify the components of a solution, including the solute and the solvent.

2. Identify the different types of solutions and how they can be classified:

   • Students should be able to distinguish between solid, liquid, and gas solutions.
   • They must also understand the difference between a saturated and unsaturated solution.

3. Understand the concept of supersaturated solutions and how they are formed:

   • Students should be able to explain what a supersaturated solution is and how it is formed.
   • They must understand that a supersaturated solution is a solution that contains more solute than the solvent can dissolve at a given temperature.

Secondary objectives:

• Develop critical thinking and problem-solving skills when working with different types of solutions.
• Promote active learning and student participation through hands-on activities and classroom discussions.

Introduction (10 - 15 minutes)

1. Review of previous content:

   • The teacher should begin the class by reviewing the concepts of mixtures and chemical reactions that were previously studied.
   • Review what a solute, a solvent, and a homogeneous mixture are. (3 - 5 minutes)

2. Presentation of problem situations:

   • The teacher can propose two situations to arouse students' interest: i. Firstly, a glass containing water and sugar, where the sugar dissolves completely in the water (solution); ii. Secondly, a glass containing water and sand, where the sand does not dissolve in the water, but only mixes (heterogeneous mixture).
   • Then, the teacher should ask students about what happens in each situation and why. (5 - 7 minutes)

3. Contextualization of the theme:

   • The teacher should explain that chemical solutions are present in our daily lives, so it is important to understand how they are formed and how they can be classified.
   • You can mention everyday examples, such as preparing juices, where water is the solvent and the juice powder is the solute, forming a solution.
   • Another example is the dissolution of salt in water, where water is the solvent and salt is the solute, forming another solution. (2 - 3 minutes)

4. Introduction to the topic:

   • The teacher should introduce the concept of supersaturated solutions, explaining that they are solutions that contain more solute than the solvent can dissolve at a given temperature.
   • You can use a practical example, such as preparing a supersaturated solution of sugar in water: if we add too much sugar to hot water and then cool it quickly, we can get a supersaturated solution.
   • Finally, the teacher should explain that supersaturated solutions are unstable and that the solute can precipitate (leave the solution) if it is disturbed in any way. (5 - 7 minutes)

Development (20 - 25 minutes)

1. Theory - Concept of Solutions and Classification (5 - 7 minutes)

   • The teacher should start by explaining the concept of chemical solutions, highlighting that they are formed when two or more substances mix and form a new substance.
   • It should be emphasized that solutions are homogeneous mixtures, that is, they are uniform in composition and cannot be separated by simple physical methods.
   • Then, the teacher should introduce the concepts of solute (the substance that is dissolved) and solvent (the substance that dissolves the solute).
   • For the classification of solutions, the teacher should explain that they can be classified into solid, liquid, and gas solutions, depending on the physical state of the substances involved.
   • It should also be emphasized that solutions can be classified as saturated, unsaturated, and supersaturated, depending on the amount of solute that can be dissolved in a given solvent at a given temperature.

2. Theory - Supersaturated Solutions and their Formation (5 - 7 minutes)

   • The teacher should introduce the concept of supersaturated solutions, explaining that they are solutions that contain more solute than the solvent can dissolve at a given temperature.
   • It should be emphasized that supersaturated solutions are unstable and that the solute can precipitate (leave the solution) if it is disturbed in any way.
   • The teacher should explain how supersaturated solutions are formed, using the practical example presented in the Introduction.
   • It is important to emphasize that, to form a supersaturated solution, it is necessary to add an excessive amount of solute to a hot solvent, and then cool the solution quickly without disturbing it.

3. Practical Activity - Preparation of Supersaturated Solutions (10 - 12 minutes)

   • The teacher should divide the class into groups and provide each group with the materials needed for the activity: a glass, hot water, and sugar.
   • Each group should add sugar to the hot water, stirring until all the sugar is dissolved.
   • Then, the groups should quickly cool the solution by placing the glass in a container of ice water or ice.
   • The teacher should instruct students to observe what happens to the solution. They should notice that the sugar begins to crystallize and precipitate, indicating the formation of a supersaturated solution.
   • Students should record their observations and conclusions in their notebooks. The teacher should walk around the room, assisting the groups, and answering any questions they may have.

4. Discussion and Conclusion (2 - 3 minutes)

   • After the activity, the teacher should gather the class and promote a discussion about the experiment.
   • The teacher should ask students what they observed and what they think happened for the solution to become supersaturated.
   • Finally, the teacher should reinforce the concept of supersaturated solutions and the importance of understanding how solutions are formed and classified.

Feedback (8 - 10 minutes)

1. Review and Reflection (3 - 4 minutes)

   • The teacher should start the Feedback by briefly reviewing the main points covered in the class, reinforcing the concept of chemical solutions, the classification of solutions (solid, liquid, and gas, saturated, unsaturated, and supersaturated), and the formation of supersaturated solutions.
   • Then, the teacher should ask students to reflect on what they have learned. They can do this silently for a minute, writing down their reflections in their notebooks.
   • The teacher should then ask some students to share their reflections with the class, giving them the opportunity to express their understanding of the concepts presented.

2. Connection with the Real World (2 - 3 minutes)

   • The teacher should now help students connect what they have learned to the real world by asking them how chemical solutions are important in their daily lives.
   • Examples such as food preparation (making juices, dissolving salt in water for cooking, etc.), cleaning (dissolving soap in water, for example), medicine (preparing intravenous solutions, etc.) and many other applications can be mentioned.
   • The teacher should encourage students to think of other examples and share them with the class.

3. Verification Questions (2 - 3 minutes)

   • To verify the students' understanding of the class content, the teacher should ask some verification questions. These questions should be open-ended, so as to allow students to express their ideas and make their understanding explicit.
   • Examples of questions might be: "What is a supersaturated solution and how is it formed?" and "Why are supersaturated solutions unstable?" .
   • The teacher should give each student enough time to think about the question and answer it. Students can also be encouraged to answer each other's questions, thus promoting interaction and discussion in the class.

4. Feedback and Closure (1 minute)

   • The teacher should close the class by thanking the students for their participation and providing general feedback on the class.
   • The importance of understanding chemical solutions for understanding various everyday phenomena should also be reinforced.
   • The teacher should remind students to study the class content and prepare for the next class.

Observation:

• It is important to remember that the times mentioned for each step are just a reference and may vary depending on the pace of the class and the students' level of understanding. The teacher should adjust the time as needed to ensure that all the Objectives of the class are met.
• In addition, the teacher should be attentive to student feedback during the class, adjusting the explanation or activity as needed to ensure that everyone is following and understanding the content.
• The teacher may also consider using visual aids, such as models or animations, to assist in understanding the concepts, especially for students who learn better through visual stimuli.
• Finally, it is important that the teacher promotes an environment of respect and collaboration, encouraging the participation of all students, and valuing their contributions to the discussion. This will help to create an environment conducive to learning and understanding the content of the class.