Objectives (5 minutes)

1. Understanding of Significant Digits: The teacher should guide students to understand the concept of significant digits and how they are used in mathematical problems. This involves discussing the nature of these digits and the reason why they can be problematic.

2. Identification of Significant Digits in Problems: After understanding the concept, the next step is for students to learn how to identify significant digits in mathematical problems. The teacher should provide varied examples and guide the students in identifying these digits.

3. Solving Problems with Significant Digits: Finally, students should be able to solve problems involving significant digits. The teacher should provide a series of problems for the class to solve together, as they gain more confidence and skill.

Secondary objectives:

• Discussion of Practical Applications: The teacher should also encourage a discussion on how significant digits can manifest in real life and in other disciplines besides mathematics, such as science and economics.

• Promoting Critical Thinking: The teacher should encourage students to think critically about the problems and the logic behind the solutions, rather than simply memorizing the steps.

Introduction (10 - 15 minutes)

1. Review of Previous Concepts: The teacher should begin the class by briefly reviewing the concepts of rational numbers and decimals, since these concepts serve as the basis for understanding significant digits. He/she can present some examples of these numbers and ask students to recall their characteristics.

2. Problem Situation 1: To arouse the students' interest, the teacher can present the following situation: "Imagine that you are calculating the average of a class's grades and the results are 6.8, 7.2, and 7.0. What would be the final average?". The teacher can ask the students to think about how they would solve this question and what challenges they might encounter.

3. Problem Situation 2: Another situation that can be presented is the following: "Imagine that you are measuring the temperature of three different points in a room and the results are 20.5°C, 21.4°C and 20.8°C. What would be the average temperature?". The teacher should emphasize that solving these problems requires attention to the digits after the decimal point.

4. Contextualization: The teacher should then contextualize the importance of significant digits, explaining that they are used to express precise measurements in a variety of fields, such as science, economics, and engineering. He/she can mention examples of real-world situations where the precision of the digits is crucial.

5. Introduction to the Topic: Finally, the teacher should introduce the topic of the class: "Today, we are going to learn about significant digits. They may seem small, but they are very important for mathematics and our daily lives. We are going to understand what they are, how to identify them, and how to work with them in complex mathematical problems.".

Development (20 - 25 minutes)

1. Activity 1: The Significant Digits Game (10 - 15 minutes)

   • Description: The teacher will divide the class into groups of 3-4 students and will provide each group with a set of cards. Each card will have a decimal number with a significant digit, such as 1.5?, 2.3?, etc. In addition, each group will receive a list of problems that they will have to solve, where the significant digit of the card will be used.
   • Execution: The students, in their groups, will have to first identify the significant digit on each card and then solve the corresponding problems using the correct technique to deal with significant digits. The objective of the game is to solve the most problems correctly in the shortest possible time.
   • Feedback: After the time is up, the teacher will collect the cards and the solutions to the problems. He/she will then review the solutions together with the class, highlighting the correct strategies for dealing with significant digits. The winning group will be the one that has solved the most problems correctly.

2. Activity 2: The Significant Digits Crossword (10 - 15 minutes)

   • Description: The teacher will provide each group of students with a sheet with a crossword that includes words related to significant digits, such as "precision", "approximation", "uncertainty", among others. In addition, there will be a crossword where students will have to fill in the blanks with the correct words.
   • Execution: The students, in their groups, will have to find the words in the crossword and fill in the blanks of the crossword. To do this, they will have to use the knowledge acquired during the class on significant digits.
   • Feedback: After the time is up, the teacher will review the solutions to the crossword and the crossword with the class, clarifying any doubts that may arise. The group that manages to solve the most words correctly will be the winner.

3. Activity 3: Creating Problems with Significant Digits (5 - 10 minutes)

   • Description: To end the class, the teacher will ask each group to create a mathematical problem that involves the use of significant digits. They will have to include the problem, the answer choices, and the correct solution.
   • Execution: The students, in their groups, will have to think and create an interesting and challenging problem. They can be inspired by the problems solved during the class or create something completely new.
   • Feedback: After the time is up, each group will present their problem to the class. The teacher and the other students will evaluate the problem and the proposed solution, providing constructive feedback. This activity will promote creativity, practical application of knowledge, and the problem-solving skills of the students.

Return (10 - 15 minutes)

1. Group Discussion (5 - 7 minutes)

   • Description: To begin the Return phase, the teacher should gather all the students and promote a group discussion about the solutions found by each team in the activities carried out. He/she can ask each group to share a solution or strategy that they consider innovative or effective.
   • Execution: The teacher can conduct this discussion by asking open-ended questions, encouraging all students to participate and express their opinions. He/she should ensure that the discussion remains focused on the use of significant digits and the logic of solving the problems.
   • Feedback: The teacher should provide feedback on the solutions presented, highlighting strengths and areas for improvement. He/she can also take the opportunity to reinforce important concepts and clarify any doubts that may still exist.

2. Connection with Theory (3 - 5 minutes)

   • Description: The teacher should then connect the activities carried out with the theory presented at the beginning of the class. He/she can briefly review the main points discussed and explain how they apply to the problems solved during the activities.
   • Execution: The teacher can do this by highlighting specific examples from the activities and explaining how the concepts of significant digits were applied to solve the problems. This will help reinforce the students' understanding of the topic.
   • Feedback: The teacher should ask the students if they can see the connection between the theory and practice, and if they feel that the activities helped them understand the topic better. He/she should be open to questions and comments from the students, encouraging an open and respectful dialogue.

3. Individual Reflection (2 - 3 minutes)

   • Description: To end the Return phase, the teacher should propose that the students do a brief individual reflection on what they have learned. He/she can give some questions to guide this reflection, such as: "What was the most important concept you learned today?" and "What questions have not yet been answered?".
   • Execution: The students will have a minute to think about these questions and write down their answers. The teacher may suggest that they share their reflections with the class, if they feel comfortable.
   • Feedback: Once all the students have had the opportunity to reflect, the teacher can comment on the answers, highlighting the most interesting insights and answering any unresolved questions. He/she should also encourage the students to continue reflecting on what they have learned after the class.

Conclusion (5 - 10 minutes)

1. Summary and Recapitulation (2 - 3 minutes)

   • Description: The teacher should begin the Conclusion phase by summarizing the main points discussed during the class. He/she should recapitulate the concept of significant digits, how to identify them in mathematical problems, and how to work with them to obtain accurate results.
   • Feedback: The teacher should ask the students to confirm that they have understood these concepts and if they have any remaining questions. He/she should clarify any confusion and reinforce the importance of significant digits in mathematics and other disciplines.

2. Theory-Practice-Application Connection (2 - 3 minutes)

   • Description: The teacher should then explain how the class connected the theory, practice, and applications of significant digits. He/she can recall the activities carried out and how they illustrated the use of significant digits in real-world, practical situations.
   • Feedback: The teacher should ask the students to share their perceptions on this connection, reinforcing the relevance of significant digits in the real world and in their everyday lives.

3. Extra Materials (1 - 2 minutes)

   • Description: The teacher should suggest additional materials for students who wish to deepen their understanding of significant digits. This could include math books, educational websites, explanatory videos, among others. The teacher should encourage the students to explore these resources on their own to complement what was learned in class.
   • Feedback: The teacher should ask the students if they have any additional material that they would like to share with the class. He/she should also be open to suggestions for other math topics that the students would like to explore in the future.

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

   • Description: To close the class, the teacher should emphasize the importance of significant digits in daily life and in different fields of knowledge. He/she can give examples of real-world situations where understanding and correctly using significant digits is crucial.
   • Feedback: The teacher can ask the students if they can think of other situations where significant digits may be relevant. He/she should encourage students to apply what they have learned in new contexts and to value mathematics as a powerful tool for understanding and solving real-world problems.