Contextualization

Theoretical Introduction

Decimal numbers are an extension of the system of integers. They allow us to represent quantities smaller than one, such as half of a pizza, or 0.5. In our numbering system, we use the comma to separate the whole part from the decimal part of a number.

Adding and subtracting decimal numbers, although they may seem simple, can be a challenge. They require students to pay attention to the correct placement of numbers, as well as the relationship between units, tens, hundreds, and decimal places such as tenths, hundredths, thousandths, etc.

The process of adding and subtracting decimal numbers is similar to that of integers. In the case of addition, for example, we must align the numbers so that the commas are in the same column. Then, we add each column, starting from the rightmost one.

Contextualization

Decimal numbers are present in our daily lives in ways we don't always realize. When we go to the supermarket and check the prices of products, we are dealing with decimal numbers. When we measure our weight or height, we are using decimal numbers. Therefore, understanding how to add and subtract decimal numbers is essential to help us in various life situations.

Furthermore, the ability to manipulate decimal numbers is a prerequisite for understanding other more advanced mathematical topics, such as operations with fractions, solving equations, or working with proportions and ratios. Therefore, mastering the addition and subtraction of decimal numbers is an important step in each student's mathematical education.

Practical Activity

Activity Title: "The Decimal Little Market"

Project Objective

This project aims to develop the skills of adding and subtracting decimal numbers in a contextualized and practical environment. Students will perform arithmetic operations as if they were buying and selling products in a little market, helping to connect mathematical knowledge with the real world.

Detailed Project Description

Students will be divided into groups of 3 to 5 participants, and each group will be responsible for managing a "Decimal Little Market." The Decimal Little Market will be an imaginary mini-market where products have prices in decimal numbers (for example, $1.25, $3.99, $0.50, and so on) and the students, as market managers, will have to perform addition and subtraction calculations with decimal numbers to manage their sales and purchases.

Required Materials

1. Sheets of paper
2. Pencils and erasers
3. Calculator (optional)
4. Imaginary products with prices in decimal numbers
5. Printed tables with prices and items from the Decimal Little Market

Detailed Step-by-Step

1. First, students must create a list of products for the Decimal Little Market. This list should include the product's name and its price in decimal numbers.

2. Students then simulate the sale of products. For example, an imaginary customer wants to buy 3 different products. Students must calculate the total value of the purchase by adding the prices of the 3 products.

3. In addition, students simulate the situation where the customer has a certain amount of money (for example, $20.00) and wants to know how much change they will receive. For this, students must subtract the total purchase amount from the amount the customer has.

4. Students must repeat these simulations with various imaginary "customers" and different combinations of products, always recording the calculations they performed.

5. After conducting the simulations, each group must prepare a report detailing the operations performed and presenting the results obtained.

Project Deliverables

The project will involve several practical activities and a written submission. The written submission will be a report that should include the following elements:

• Introduction: Students must contextualize the project, explaining what a Decimal Little Market is and why knowledge of adding and subtracting decimal numbers is important. Additionally, they should describe the project's objective and how it was developed.

• Development: In this part, students must detail the activities they carried out. It should describe the process of creating the product list, how the sales simulations were conducted, the mathematical operations performed, and the results obtained.

• Conclusions: Students must summarize the main points of the project, highlighting what they learned from the experience and how this learning can be applied in real situations. They should also reflect on any difficulties encountered and how they were overcome.

• Bibliography: Students must include a list of all resources they used to learn about adding and subtracting decimal numbers.

The report should be written clearly and organized, demonstrating an understanding of the topic and the teamwork carried out during the project. Students should strive to contextualize the mathematics used in practical situations, reinforcing the connection between acquired knowledge and its application in the real world.