Contextualization
Proportional relationships, a core concept of mathematics, are present in our daily lives more than we often realize. From calculating the price of items on sale to determining the amount of ingredients needed for a recipe, we constantly encounter situations where two variables are related to each other in a consistent and predictable way. Understanding these relationships and the graphical representation of them is not only fundamental to the field of mathematics but also to fields as diverse as economics, physics, and more.
When two variables are directly proportional, as one variable increases, the other variable also increases at a constant rate. This constant rate of change is the key characteristic of a proportional relationship. For example, if we're driving at a constant speed, the distance we cover and the time it takes us to cover that distance are directly proportional.
The graphical representation of proportional relationships is done through a straight line that passes through the origin (0,0). The slope of this line represents the constant of proportionality, which is the rate of change. The steeper the line, the greater the rate of change, and vice versa. The yintercept of this line is always zero, indicating that when the independent variable is zero, the dependent variable is also zero.
Understanding how to construct and interpret these graphs is not only a key skill in mathematics but is also a crucial tool in analyzing and making predictions about realworld situations. By learning about graphs of proportional relationships, we're equipping ourselves with a powerful tool for understanding the world around us.
Resources
Here are some resources that you can use to deepen your understanding of the topic and to help you with the project:
 Khan Academy: Proportional Relationships
 Math is Fun: Graphing Proportional Relationships
 BBC Bitesize: Proportional Relationships and Graphs
 Math Antics: Proportional Relationships and Graphs
 Book: "Big Ideas Math: Modeling Real Life  Student Edition" by Houghton Mifflin Harcourt
Remember, these resources are not exhaustive, and you should feel free to explore other sources as well. The more you delve into the topic, the better you'll understand it.
Practical Activity
Activity Title: "Exploring Proportional Relationships through RealWorld Scenarios"
Objective of the Project:
To understand and apply the concept of proportional relationships, and to create graphical representations of these relationships based on realworld data.
Detailed Description of the Project:
In this project, groups of 3 to 5 students will work collaboratively to conduct a survey on a realworld topic of their interest. The survey should involve two variables that they believe are in a proportional relationship. The students will then use the collected data to create a graph, where the xaxis represents one variable, the yaxis represents the other variable, and the data points on the graph represent the results of their survey.
Necessary Materials:
 Survey questions
 Survey responses
 Graph paper or graphing software
 Ruler (if using graph paper)
 Pencil
 Calculator
Detailed Stepbystep for Carrying Out the Activity:

Brainstorming: As a group, brainstorm a list of topics they are interested in and that they believe might involve a proportional relationship. For example, the number of hours spent studying and the grade received on a test, or the price of a product and the amount of product received.

Designing a Survey: Once the group has chosen a topic, they should design a survey that will allow them to collect data on the two chosen variables. The survey should be designed in a way that the answers to one question can be directly proportional to the answers to another question.

Conducting the Survey: Carry out the survey on a sample population. The sample size should be large enough to provide a meaningful representation but small enough to manage effectively.

Collecting and Organizing Data: Collect the responses and organize the data in a way that clearly shows the relationship between the two variables.

Creating the Graph: Using the collected data, create a graph with the xaxis representing one variable and the yaxis representing the other variable. Make sure to choose appropriate scales for the axes.

Interpreting the Graph: Analyze the graph. Is it a straight line that passes through the origin? What is the slope of the line? What does the slope represent in the context of the survey?

Writing the Report: Each group member should contribute to a detailed report documenting their project. The report should cover:
 Introduction: Contextualize the chosen theme, its relevance, and realworld application.
 Development: Explain the theory behind proportional relationships, detail the process of the activity, and present and discuss the obtained results.
 Conclusion: Revisit the main points, state the learnings obtained, and draw conclusions about the project.
 Used Bibliography: Indicate the sources they relied on to work on the project.
Project Deliverables:
At the end of the project, each group should submit a written report and a graphical representation of their data. The report should be a comprehensive document that details all aspects of the project, from the initial brainstorming to the final interpretation of the graph. It should include the theoretical concepts learned, the methodology used, the results obtained, and the conclusions drawn. The graphical representation should be a clear, welllabeled graph that accurately represents the data collected in the survey.
This project is designed to take approximately 10 to 15 hours per participating student to complete. It will test not only your understanding of proportional relationships but also your ability to work collaboratively, think critically, and problemsolve. Remember, the key to success in this project is not just getting the right answer but demonstrating a deep understanding of the concepts and an ability to apply them in a realworld context. Good luck!