When family members share a wireless plan, how should they split the bill? What if someone goes over the maximum allotted messages, voice minutes, or megabytes of data? And when should they change to a different plan?
In this lesson, students use proportional reasoning to predict whether a family will exceed their wireless plan allotment. They write and evaluate numerical expressions to decide how to split the bill fairly, and explain whether it makes sense to upgrade their plan.
Students will
Use proportional reasoning to predict 30 days of cell phone usage based on 1, 7, and 15 days
Calculate the monthly bill for two siblings on a family plan, including flat-rate items and overages
Based on his/her usage, determine how much each sibling should pay
Evaluate alternative wireless plans, and decide whether up- or downgrading would better fit their wireless behavior and save them money in the future
Before you begin
Students should be able to perform operations on decimals and apply the order of operations. The lesson applies unit rates and involves proportional reasoning, but extensive prior experience with these is not assumed. The focus in this lesson is more on constructing and communicating logical arguments than it is on sophisticated mathematics.
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How much does it cost to drive at different speeds? Students use unit rates and proportions to explore how a car's fuel economy changes as it drives faster and faster.
Who should buy health insurance? Students use percents and expected value to explore the mathematics of health insurance from a variety of perspectives.
Topic:
Number System (NS), Ratios and Proportional Relationships (RP), Statistics and Probability (SP)
How do aspect ratios affect what you see on TV? Students use ratios to explore why the image doesn't always fit on the screen, and examine how letterboxing might affect their favorite movies.
Topic:
Geometry (G), Ratios and Proportional Relationships (RP)
How have temperatures changed around the world? Students compare current temperatures to historical averages, and add and subtract positive and negative numbers to explore how the climate has changed in various cities over time.
How has the pace of human innovation changed over time? Students order and subtract integers to explore major milestones in human history and debate whether humans are innovating faster than we can keep up with the consequences.
How long does it take to donate to Locks of Love? Students write and solve linear equations to determine how long it would take to donate a wig’s worth of hair and discuss ways they can support peers with conditions like Leukemia and alopecia.
Should the U.S. get rid of the penny? Students operate with decimals to calculate the total costs to produce different U.S. coins. Students debate eliminating the penny and then consider a world with no physical money at all.
Is it a good idea to rent a storage unit? Students write and solve multi-step equations to evaluate whether storage unit rentals are worth the cost and make recommendations for when people should store, sell, donate, or toss their unused stuff.
Topic:
Expressions and Equations (EE)
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Mathalicious lessons provide teachers with an opportunity to teach standards-based math through real-world topics that students care about.
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Topic:
Building Functions (BF), Interpreting Categorical and Quantitative Data (ID), Interpreting Functions (IF), Linear, Quadratic, and Exponential Models (LE), Seeing Structure in Expressions (SSE)