Phone Plan Showdown — Unit 9 Culminating Project

Step 1 of 6

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Key Words

Learn these 5 mathematical words before you begin

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Independent Variable (x or g)

The quantity that changes independently. In our project, it's the gigabytes of data you use.

g = 5 GB used

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Dependent Variable (y or C)

The quantity that depends on the independent variable. Here, it is the total monthly cost.

C = $70 total cost

⚙️

Equation

A mathematical sentence with an equals sign showing how the output is calculated from the input.

C = 10g + 20

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Data Table

A structure that lists multiple inputs side-by-side with their corresponding outputs.

5 GB matches $70

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Line Graph

A visual model of the relationship. Points are plotted on grid axes and connected with a line.

Coordinates: (5, 70)

✅ Read each key term carefully. When you understand how independent data relates to dependent cost, click Next Step.

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Step 1 — Design Your Plan & Equation

Choose a flat monthly fee and a rate per GB, then write the cost equation

Your job: Set the price levels for your custom phone plan. Enter a flat fee (base price) and a rate for each gigabyte of data you use.

📊 Research you need for this step📊 Investigación que necesitas para este paso

📱 T-Mobile — Phone Plans ↗T-Mobile — Planes de teléfono ↗ Fill in: The ___ plan costs $___ per line each month.Completa: El plan ___ cuesta $___ por línea al mes. 📶 Verizon — Phone Plans ↗Verizon — Planes de teléfono ↗ Fill in: Base $___ per month plus $___ per line (y = ___x + ___).Completa: Base $___ al mes más $___ por línea (y = ___x + ___). 🟢 Mint Mobile — Plans ↗Mint Mobile — Planes ↗ Fill in: ___ GB costs $___ per month.Completa: ___ GB cuesta $___ al mes.

🟠 Level 0: Cost has two parts. Step 1: flat fee + (rate × gigs). Tiny example: $10 + $5×2 = $20. Starter: “My cost is $___.” 🟠 Nivel 0: El costo tiene dos partes. Paso 1: tarifa fija + (tasa × gigas). Ejemplo: $10 + $5×2 = $20. Empieza: “Mi costo es $___.”

🟢 Level 1 tip: Try round, friendly values. For example, choose a $20 flat fee and a $10 cost per GB. Your equation will look like: C = 10g + 20.

LEVEL 2 CHALLENGE
Feel free to pick decimal numbers (e.g. $8.50 per GB, $15 base fee). Write your equation to perfectly model your choices!

💵 Flat Monthly Fee ($)

⚡ Cost per Gigabyte of Data ($/GB)

✍️ Write your Cost Equation (use C for cost and g for gigabytes)

Need help writing the equation?

Your equation shows how to find the dependent variable (C) from the independent variable (g). Multiply the rate per GB by g, then add the flat monthly fee.
Example: $10/GB and $20 flat fee → C = 10g + 20.

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Step 2 — Generate Your Data Table

Calculate the total monthly cost for different amounts of data

Your job: Calculate the monthly costs for 0 GB, 1 GB, 2 GB, 5 GB, and 10 GB of data based on your step 1 parameters.

🟠 Level 0: Put in a number for g. Step 1: multiply gigs by rate, then add the fee. Tiny example: g=3, $5×3=$15, +$10=$25. Starter: “For ___ GB, cost = $___.” 🟠 Nivel 0: Sustituye un número por g. Paso 1: multiplica gigas por tasa, luego suma la tarifa. Ejemplo: g=3, $5×3=$15, +$10=$25. Empieza: “Para ___ GB, costo = $___.”

🟢 Level 1 tip: Multiply the gigabytes (g) by your rate, then add the base flat fee.

LEVEL 2 CHALLENGE
Write down your coordinates as (g, C) ordered pairs in the last column. Example: (5, 70).

Data Used (g GB)	Equation Work / Process	Total Cost ($ C)	Ordered Pair (g, C)
0 GB	$0 base fee
1 GB	rate × 1 + fee
2 GB	rate × 2 + fee
5 GB	rate × 5 + fee
10 GB	rate × 10 + fee

Need help with calculations?

If your plan is C = 10g + 20:
• For 0 GB: 10(0) + 20 = $20
• For 1 GB: 10(1) + 20 = $30
• For 5 GB: 10(5) + 20 = $70

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Step 3 — Graph and Analyze Your Plan

Look at your plan's visual representation and answer coordinate questions

Your job: Examine the line graph generated below and answer the analysis questions.

📈 Coordinate of y-intercept 💬 What does this point represent in real life?

📱 Cost for 8 GB of data ($) 💬 How can you find this using the graph or equation?

⚡ Is this relationship proportional or non-proportional? 💬 Why?

🌎 Real-World Market Prices

Below are real average competitor prices. Compare your plan's cost for 5 GB of data ($0.00) to these tiers:

Plan Tier	Average Price	Description
Basic Plan (Limited Data)	$15 – $30 / month	Includes 2GB to 5GB of data. Best for light users.
Mid-Tier Plan (Standard)	$35 – $48 / month	Includes 10GB to 15GB of data. Standard family plan.
Unlimited Data Plan	$50 – $80 / month	Unlimited data, speeds may slow down after 50GB.

How does your plan compare to market prices for 5 GB of data? Write 2 sentences.

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Step 4 — Compare with a Partner

Interview a classmate about their plan, graph both, and find the cheaper option

Your job: Enter details from a classmate's phone plan. Compare costs side-by-side using a double-line graph and table.

📊 Research you need for this step📊 Investigación que necesitas para este paso

📊 WhistleOut — Compare Carriers ↗WhistleOut — Compara operadores ↗ Fill in: Plan A: $___/mo; Plan B: $___/mo — compare over ___ months.Completa: Plan A: $___/mes; Plan B: $___/mes — compara en ___ meses.

👤 Partner's Name 💵 Partner's Flat Monthly Fee ($)

⚡ Partner's Cost per GB ($/GB) 📝 Partner's Equation (use C and g)

📈 Cost Comparison Table

Data Used (GB)	Your Plan Cost	Partner's Plan Cost	Cheaper Plan
Enter classmate details and click compare.

❓ Based on your calculations, who has the cheaper plan for 5 GB?

💬 Reflection: Under what conditions is your plan cheaper? Under what conditions is your partner's plan cheaper? Explain using the steepness (rate) and starting points (y-intercept) of your lines.

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Step 5 — Complete and Submit

Write your sales pitch, review the rubric, and download your final report

Your job: Write a pitch explaining why your plan is a great choice. Review your checklist, and generate the final report for your teacher.

✍️ Your Pricing Presentation Pitch (3-5 sentences)

✅ Project Checklist

I defined the independent and dependent variables.
I wrote and validated the correct equation for my plan.
I completed and verified my data table.
I analyzed the graph (y-intercept and proportionality).
I compared my plan with a classmate's plan side-by-side.
I wrote a pricing presentation pitch using my real numbers.

📊 Rubric — How You Are Scored

Skill	4 — Expert	3 — Proficient	2 — Developing
Variables & Equation (6.AT.11)	Variables defined correctly; equation represents rate and flat fee perfectly.	Variables defined; equation matches flat fee and rate correctly.	Equation has minor arithmetic or formatting errors.
Data Table	Table is 100% correct; process column shows complete step-by-step arithmetic.	Table is correct with minor work missing.	Multiple calculation errors in costs or ordered pairs.
Line Graph Analysis	Intercept, 8GB cost, and proportionality identified correctly with deep conceptual explanations.	Correct answers with simple explanations.	Incorrect intercept or calculation; struggles with proportionality.
Peer Comparison	Side-by-side table correct; detailed explanation of which plan is better under different data limits.	Comparison table correct; identifies cheaper plan at 5 GB.	Comparison incomplete or has errors.
Pitch & Presentation	Uses real mathematical numbers, equation, and graphs to pitch plan logically.	Pitch is complete and uses some plan numbers.	Pitch is too short or doesn't connect math to real life.