Objectives (5 - 10 minutes)

1. Understand the conversion between units of mass and volume: Students should be able to understand the concept of conversion between different units of measure of mass and volume, such as kilograms and liters, and be able to apply this knowledge to solve simple problems.

2. Identify problem situations involving mass and volume conversions: Students should be able to identify everyday situations that can be solved through mass and volume conversions, developing the ability to apply mathematical knowledge in a practical way.

3. Develop logical reasoning and problem-solving skills: Through the study of mass and volume conversions, students will be encouraged to develop logical reasoning and problem-solving skills, which are essential for learning mathematics and for everyday life.

Introduction (10 - 15 minutes)

1. Review of previous content: The teacher starts the lesson by reminding students about the basic concepts of mass and volume measurements, such as kilograms, grams, liters, and milliliters. Simple and contextualized questions can be asked to ensure understanding, such as "If I want to measure the amount of water in a glass, which unit of volume measurement would I use?"

2. Problem situation 1: "The cake party": The teacher presents the following situation: "Imagine that at a birthday party, the teacher needs to divide a cake into equal parts for all the students in the class. However, she only has a scale to measure the whole cake. How could she use the scale to know the weight of each piece of cake?" This problem introduces the idea of converting the mass from one unit (the whole cake) to another unit (the weight of each piece).

3. Problem situation 2: "The refreshing juice": The teacher presents the following situation: "Imagine you want to make orange juice. You have a glass that measures 200 ml and the juice recipe says you need 500 ml of juice. How could you use the glass to measure the amount of juice you need?" This problem introduces the idea of converting the volume from one unit (the glass) to another unit (the required amount of juice).

4. Contextualization of the subject's importance: The teacher explains that the ability to convert between units of mass and volume is very important in daily life, as it allows us to perform simple tasks such as measuring ingredients for cooking and understanding information on product labels. Additionally, it is a fundamental skill for the study of sciences and other disciplines.

5. Introduction to the lesson topic: The teacher introduces the lesson topic, explaining that students will learn how to convert between units of mass and volume, and how to use this skill to solve practical problems. He/she emphasizes that by the end of the lesson, students will be able to use this skill to solve the presented problems and others they may encounter in their daily lives.

Development (20 - 25 minutes)

1. Activity 1: "Measuring with everyday objects" (10 - 15 minutes)

   1.1. Preparation: The teacher should bring different objects from his/her home or school that can be used to illustrate the conversion of mass and volume. For example, a milk carton, an apple, a soda can, a water bottle, etc.

   1.2. Step by step:

    1.2.1. The teacher presents each object, asking students which unit of measurement they would use to describe the mass or volume of the object. For example, they could say they would use grams to measure the mass of the apple, or milliliters to measure the volume of the water bottle.
    
    1.2.2. Next, the teacher asks students to estimate the mass or volume of each object. They can use the unit of measurement they consider most appropriate.
    
    1.2.3. Then, the teacher uses a scale and a graduated cylinder (or measuring cup) to measure the mass and volume of each object, respectively. He/she should involve the students in the process, asking for their help in making the measurements.
    
    1.2.4. Finally, the teacher discusses with the students about the estimates they made and the actual measurements, highlighting the importance of using the correct unit of measurement and how the conversion between units can help us better understand quantities.
   

2. Activity 2: "Conversion in the kitchen" (10 - 15 minutes)

   2.1. Preparation: The teacher brings a selection of ingredients used in the kitchen, such as flour, sugar, salt, water, etc., and some measuring utensils, such as spoons, cups, glasses, etc.

   2.2. Step by step:

    2.2.1. The teacher presents a simple recipe to the students, such as a cake recipe, and asks them which ingredients they need to measure and which units of measurement they would use.
    
    2.2.2. Next, the teacher asks students to, in groups, convert the mass and volume measurements from the recipe to other units. For example, if the recipe calls for 200g of flour, they should convert this measurement to kilograms, or if the recipe calls for 250ml of milk, they should convert it to liters.
    
    2.2.3. The teacher circulates around the room, guiding and correcting the students, if necessary.
    
    2.2.4. Then, the teacher asks students, again in groups, to use the available measuring utensils to measure the quantity of each ingredient they converted.
    
    2.2.5. Finally, the teacher discusses with the students about the measurements they made, highlighting the importance of using the correct unit of measurement and how the conversion between units can help us follow a kitchen recipe.
   

Both activities are designed to be interactive and engaging for students and to help them understand and apply the concept of mass and volume conversion in a practical way. The teacher can choose the activity that best suits the class dynamics or even carry out both, if time allows.

Feedback (10 - 15 minutes)

1. Group discussion (5 - 7 minutes)

   1.1. Group division: The teacher divides the class into groups and asks each group to share the solutions or discoveries they found during the practical activities. Each group should present, for example, a conversion they made in the "Conversion in the kitchen" activity and how they measured the quantity of the converted ingredient.

   1.2. Connection with theory: After each presentation, the teacher should ask questions to understand how students arrived at their answers and how they applied the concept of mass and volume conversion. For example, the teacher may ask: "How did you decide which unit of measurement to use for the conversion?" or "Why is it important to use the correct unit of measurement when making a conversion?"

   1.3. Teacher feedback: The teacher should provide positive and constructive feedback, reinforcing good practices and correcting any misunderstandings. It is important for the teacher to value the effort and participation of all students, creating a safe and encouraging learning environment.

2. Individual reflection (3 - 5 minutes)

   2.1. Reflection questions: The teacher proposes two questions for students to reflect individually on what they learned in the lesson. The questions could be: "What was the most challenging part of the mass and volume conversion activity and why?" and "How can you use what you learned today about mass and volume conversion in real situations?"

   2.2. Time to think: The teacher gives students a minute to think about their answers.

   2.3. Optional sharing: The teacher offers the opportunity for students to share their answers with the class, if they feel comfortable. The goal is to promote self-reflection and metacognition, skills that can help students become more autonomous and effective learners.

3. Conclusion (2 - 3 minutes)

   3.1. Reinforcement of content importance: The teacher concludes the lesson by reinforcing the importance of the content learned, highlighting how the ability to convert between units of mass and volume is useful in daily life, whether for cooking, shopping, measuring the amount of water we drink, among others.

   3.2. Encouragement for practice: The teacher encourages students to practice mass and volume conversion at home whenever they have the opportunity, and to share their experiences in the next lesson. This helps to consolidate learning and promote the application of knowledge in real situations.

Conclusion (5 - 10 minutes)

1. Summary of key points: (2 - 3 minutes)

   1.1. Theory review: The teacher briefly recaps the main concepts covered during the lesson. He/she reminds students about the definition of mass and volume, the most common units of measure (kilograms, grams, liters, milliliters), and the importance of using the correct unit of measurement when making a conversion.

   1.2. Application in practice: Next, the teacher highlights how these concepts were applied in the practical activities. He/she emphasizes how students used mass and volume conversion to measure everyday objects and to follow a kitchen recipe.

2. Connection between theory and practice: (1 - 2 minutes)

   2.1. Explanation: The teacher explains how the lesson connected theory (mass and volume conversion) with practice (measuring everyday objects and converting measurements in a recipe). He/she emphasizes that theory provides the concepts and tools necessary to solve practical problems in daily life.

   2.2. Examples: The teacher can give examples of real-life situations where mass and volume conversion is necessary, such as when cooking and needing to adapt a recipe for more or fewer people, or when buying food and wanting to compare prices per kilogram or per liter.

3. Extra materials: (1 - 2 minutes)

   3.1. Book suggestions: The teacher can suggest some textbooks that address the subject in a playful and age-appropriate manner, such as "The Magical World of Measures" by Ana Cristina Melo, and "Adventures with Measures" by António Mota.

   3.2. Online activities: The teacher can also recommend some websites or apps that offer games and interactive activities on mass and volume conversion, such as "Fun Mathematics" (www.matematicadivertida.com.br) and "Khan Academy" (www.khanacademy.org).

4. Importance of the subject in daily life: (1 - 2 minutes)

   4.1. Contextualization: Finally, the teacher reinforces the importance of the content learned, contextualizing it with students' daily lives. He/she explains that the ability to convert between units of mass and volume is very useful in various everyday situations, such as when cooking, shopping, measuring the amount of water we drink, among others.

   4.2. Encouragement for practice: The teacher encourages students to practice mass and volume conversion at home whenever they have the opportunity, and to share their experiences in the next lesson. This helps to consolidate learning and promote the application of knowledge in real situations.