The Block: CASE 15

Why did the total change at checkout?

Consumer math and disclosure

1: STORY

What happened?

In the starter, a student has $14.00 and an online cart reaches $17.46 after tax and shipping. The packet is a separate checkout exercise about headphones: a $19.99 member shelf price and a $26.49 receipt. Those figures cannot be merged into one transaction. Both situations raise the same useful question: what conditions and additions separate an advertised price from a payable total?

Lupa reads beyond the large shelf number. The $19.99 offer requires a free account. The promotion terms add that the shopper must sign in and identify $24.99 as the regular price. Free account describes one condition's cost; it does not mean the merchandise is free, the tax disappears, or every shopper receives the discount automatically.

Duda separates two calculations. The receipt's merchandise amount exceeds the member price by $5.00. Its $1.50 tax then brings $24.99 to $26.49. Tax accounts for only part of the difference between the shelf number and the total. The receipt matches the regular merchandise price, but it does not tell us whether the shopper signed in.

Voz turns the investigation into a checklist usable before a purchase. Check the exact item, eligibility conditions, sign-in step, merchandise subtotal, added charges, and displayed total. Preserve the offer and ask the store about an unexplained mismatch. The sources support arithmetic and a question about the transaction; they do not settle whether the signage satisfied consumer law.

2: EVIDENCE

Open the receipts.

These are NPW practice documents. Real-world sources are credited separately below.

SOURCE A — Shelf tag

NPW practice document. Headphones: $19.99. “Member price with free account.”

What it establishes: Shows conditional advertised price.

Question while reading: What condition is attached?

SOURCE B — Receipt

NPW practice document. Merchandise $24.99; sales tax $1.50; total $26.49.

What it establishes: Shows amount actually charged and tax.

Question while reading: Which part differs from the shelf tag?

SOURCE C — Promotion terms

NPW practice document. “$19.99 price applies after account sign-in; regular price $24.99.”

What it establishes: Explains price condition. It does not establish whether signage was sufficiently clear under consumer law.

Question while reading: What could a customer ask the store to explain?

Source A advertises a conditional $19.99 member price. Source C explains the sign-in condition and $24.99 regular price. Reading both prevents treating the largest printed number as an unconditional offer. Neither source establishes whether this shopper created an account, signed in correctly, or met any other transaction-specific requirements.

Source B shows the actual merchandise charge, tax, and total. Its arithmetic is consistent: $24.99 plus $1.50 equals $26.49. The $5.00 merchandise difference matches the gap between regular and member prices. That pattern supports asking whether the discount applied, not declaring that a cashier made an error or that the promotion was lawful.

3: PRACTICE

Try your read.

What explains the documented difference most precisely?The receipt has a $5.00 higher merchandise price plus $1.50 tax.The entire $6.50 difference is sales tax.The receipt proves the customer was signed in.

Check the reasoning

The sources separate the merchandise-price gap from tax. They do not document the customer’s sign-in status.

FIRST READ: What did you think was happening before you opened the sources?LUPA FOUND THE ORIGINAL: Which source is closest to the event or rule? Why?ONDA CHECK: Who could experience the situation differently, and through what mechanism?WHAT ARE WE MISSING? Name one fact you cannot establish.

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4: TASK

Make a “before you buy” checklist.

Make a “before you buy” checklist. Include one clear claim or question, at least two source references, one statement of uncertainty/scope, the person or office with relevant authority, and one realistic next step.

Compare with a worked response

My before-you-buy checklist is: confirm the headphones match the tag; notice that $19.99 is a member price (Source A); check the account sign-in requirement and $24.99 regular price (Source C); compare the merchandise subtotal before adding tax; and review the final total before paying. This receipt charges $24.99 plus $1.50 tax, totaling $26.49 (Source B), so tax alone does not explain the difference from $19.99. I would keep the tag and receipt and ask store customer service whether the member discount should have applied. The packet does not show sign-in status or establish whether the promotion's disclosure met legal requirements.

Before you close the case

What is one thing the strongest source establishes?
What can it not establish?
Who can decide or clarify the issue?
What changed between your first read and your read now?

One step further

How would your checklist change for a ticket advertised at one price but sold with a service fee and optional add-ons?

Behind the Case: educator notes

45–55 min core, 80–100 min full

Teaching moves

Ask students to annotate two separate differences: member versus regular merchandise price, then merchandise price versus tax-inclusive total.
Give pairs shopper questions that can be answered by each source and one question the packet cannot resolve.
Have students test the checklist on the starter without borrowing headphone prices, explaining which missing online-cart details they would need.

Supports and response choices

Preview the three most important terms with examples.
Allow oral, typed, handwritten, or visual-map response when format is not the learning goal.
Keep the original source excerpt beside a plain-language annotation.
Keep formal English institutional terms visible beside translated explanation.
Advanced extension: compare the practice document with a real current local source.

Criterion	Beginning	Developing	Strong	Advanced
Accuracy & scope	Repeats claim.	Mostly accurate; scope incomplete.	Accurate and properly scoped.	Accurate, scoped, and explicit about uncertainty.
Evidence	Little or unrelated.	Relevant source, sometimes overstated.	Explains what sources establish.	Compares sources and limits.
Authority	Names actor without role.	Plausible authority.	Explains who decides and why.	Maps proposal, approval, implementation, review.
Communication	Vague or audience-mismatched.	Main point understandable.	Clear, specific, audience-aware.	Clear, accessible, precise, well-qualified.