Week 9 Argument Workshop: Testing the Samples in a Letter About City Bike-Share

Part 1 — The Big Picture

A claim about a whole city can rest on a few hundred voices, and whether it deserves trust depends far more on how those voices were gathered than on how many there are. This week you learned to name a population and a sample, to spot a sample that is too small, biased, or skewed by nonresponse, to tell a random sample from whoever happened to answer, to catch a story standing in for a trend, and to test a comparison by the similarities that bear on its conclusion. In this workshop you lay out a short letter proposing city bike-share, run the sampling check on its two surveys, test its anecdote and its analogy, build a short argument of your own with its strongest objection and a reply, and then catch a chatbot making the slips this week warns about.

Time budget: Plan for about 90 minutes.

Part 2 — The Task

Guiding question: In an illustrative letter proposing city bike-share, which survey is the better guide to how residents feel, and which of the letter's other reasons, a vacation story and a comparison with a college campus, bear on its conclusion?

Workshop data: Eight sentences from an illustrative letter proposing a city bike-share program

Source: An illustrative letter to a city newsletter, written for this workshop and printed in full in Part 4; it comes from no real person, city, office, council, or shop.

• Rows: 8 sentences, one row each in the sorting table
• Columns: sentence, role in the argument, and the check to run
• Source text: the full letter: Our city should launch a bike-share program with 20 stations downtown. The city's transportation office posted a poll on its website, and 1,200 of the 1,500 people who answered said they want bike-share. The city has 75,000 adult residents. My neighbor rode a shared bike on vacation and said it was the best way to see that city, so riders here will love it too. A city is like a college campus, and campuses with bike-share have plenty of riders, so our city will too. A second survey drew 200 adult residents at random from the city's utility-billing list, and 110 of them said they want bike-share. One council member objects: the stations would take up 40 downtown parking spaces, and small shops worry that customers who drive will have nowhere to park. So many people answered the online poll that its result has to be right.

Part 3 — Materials & Procedure

Tools and materials

• Pen and paper or any free diagramming tool for argument maps and Venn diagrams; a free spreadsheet (Google Sheets, or any free spreadsheet) for the frequency, risk, and two-way tables; the Stanford Encyclopedia of Philosophy and the Internet Encyclopedia of Philosophy for named concepts; and one approved chatbot used as a sparring partner whose arguments the student maps and tests before trusting them

Ways of working

• map-the-argument
• test-the-reasoning
• build-and-defend

Procedure

1. Read the whole letter in the first table of Part 4 twice: once for what it proposes, and once sentence by sentence. Tool: Pen and paper or any free diagramming tool for argument maps and Venn diagrams; a free spreadsheet (Google Sheets, or any free spreadsheet) for the frequency, risk, and two-way tables; the Stanford Encyclopedia of Philosophy and the Internet Encyclopedia of Philosophy for named concepts; and one approved chatbot used as a sparring partner whose arguments the student maps and tests before trusting them. Check: You can say in one sentence what the letter asks the city to do.
2. In the Role column of the sorting table, label each sentence as the main conclusion, a survey report, a supporting reason, a background figure, or the objection, and in the last column name the check you will run, if any. Tool: Pen and paper or any free diagramming tool for argument maps and Venn diagrams; a free spreadsheet (Google Sheets, or any free spreadsheet) for the frequency, risk, and two-way tables; the Stanford Encyclopedia of Philosophy and the Internet Encyclopedia of Philosophy for named concepts; and one approved chatbot used as a sparring partner whose arguments the student maps and tests before trusting them. Check: Exactly one row is labelled the main conclusion, exactly one is labelled the objection, and every row has a role.
3. Fill in the sampling table for the online poll in sentence 2 and the survey in sentence 6: who could end up in each sample, how they got in, which trap applies (too small, biased, nonresponse, or none of the three), and which survey is the better guide to all adult residents. Tool: Pen and paper or any free diagramming tool for argument maps and Venn diagrams; a free spreadsheet (Google Sheets, or any free spreadsheet) for the frequency, risk, and two-way tables; the Stanford Encyclopedia of Philosophy and the Internet Encyclopedia of Philosophy for named concepts; and one approved chatbot used as a sparring partner whose arguments the student maps and tests before trusting them. Check: Each survey's row says how its people got into the sample before it names a trap.
4. Fill in the reasons table for sentences 4 and 5: for the vacation story, count the cases it rests on and name the fallacy if there is one; for the campus comparison, list a similarity that bears on the conclusion, name a disanalogy, and give a verdict. Tool: Pen and paper or any free diagramming tool for argument maps and Venn diagrams; a free spreadsheet (Google Sheets, or any free spreadsheet) for the frequency, risk, and two-way tables; the Stanford Encyclopedia of Philosophy and the Internet Encyclopedia of Philosophy for named concepts; and one approved chatbot used as a sparring partner whose arguments the student maps and tests before trusting them. Check: Sentence 4 has its cases counted, and sentence 5 has at least one similarity and one disanalogy written out before its verdict.
5. Type the four survey figures into a free spreadsheet, one per cell: the poll's 1,200 yes answers, the poll's 1,500 answers, the 75,000 residents, and the survey's 110 yes answers out of 200. In separate cells, divide the poll's yes answers by its answers and multiply by 100; divide the poll's answers by the residents and multiply by 100; take the poll's answers away from the residents; and divide the survey's yes answers by 200 and multiply by 100. Tool: Pen and paper or any free diagramming tool for argument maps and Venn diagrams; a free spreadsheet (Google Sheets, or any free spreadsheet) for the frequency, risk, and two-way tables; the Stanford Encyclopedia of Philosophy and the Internet Encyclopedia of Philosophy for named concepts; and one approved chatbot used as a sparring partner whose arguments the student maps and tests before trusting them. Check: Each of the four figures in the tally table appears in its own cell, and each matches the same step worked by hand.
6. Write your own short argument on the same question in the build table: a conclusion, two premises that each bear on it, the strongest objection someone could raise stated as its holders would state it, and your reply. You may argue for either answer. Tool: Pen and paper or any free diagramming tool for argument maps and Venn diagrams; a free spreadsheet (Google Sheets, or any free spreadsheet) for the frequency, risk, and two-way tables; the Stanford Encyclopedia of Philosophy and the Internet Encyclopedia of Philosophy for named concepts; and one approved chatbot used as a sparring partner whose arguments the student maps and tests before trusting them. Check: Each premise bears on your conclusion, any survey you cite is the better guide, the objection is stated as fairly as its best defender would state it, and the reply engages it.
7. Paste your completed tables into one approved chatbot with the prompt in Part 6, then check its answer against the letter, your tables, and this week's chapter, or complete the equivalent route's marked-up analysis instead. Tool: Pen and paper or any free diagramming tool for argument maps and Venn diagrams; a free spreadsheet (Google Sheets, or any free spreadsheet) for the frequency, risk, and two-way tables; the Stanford Encyclopedia of Philosophy and the Internet Encyclopedia of Philosophy for named concepts; and one approved chatbot used as a sparring partner whose arguments the student maps and tests before trusting them. Check: You have quoted at least two of the chatbot's statements, or of the printed analysis, and corrected each with evidence.

Fallback route

When to use it: Use this route if no spreadsheet is available.

Work the four figures in the tally table by hand, with each division and subtraction written out on paper. Then complete every other table, analysis question, and the critique step, and submit the same items for equal credit.

This route earns the same credit as the primary route.

Part 4 — The Scaffold

The letter comes first: give each of its eight sentences a role before you test anything.

Student scaffold table 1

Sentence	Role in the argument	Check to run, if any
S1. Our city should launch a bike-share program with 20 stations downtown.
S2. The city's transportation office posted a poll on its website, and 1,200 of the 1,500 people who answered said they want bike-share.
S3. The city has 75,000 adult residents.
S4. My neighbor rode a shared bike on vacation and said it was the best way to see that city, so riders here will love it too.
S5. A city is like a college campus, and campuses with bike-share have plenty of riders, so our city will too.
S6. A second survey drew 200 adult residents at random from the city's utility-billing list, and 110 of them said they want bike-share.
S7. One council member objects: the stations would take up 40 downtown parking spaces, and small shops worry that customers who drive will have nowhere to park.
S8. So many people answered the online poll that its result has to be right.

Run the sampling check on the letter's two surveys before you trust either figure.

Student scaffold table 2

Survey	Who could end up in the sample	How they got in	Trap: too small, biased, nonresponse, or none	Better guide to all adult residents?
Online poll (S2)
Random survey (S6)

Test the letter's other two reasons: count the cases behind the story and weigh the comparison.

Student scaffold table 3

Sentence	Cases or similarities that bear on the conclusion	Disanalogy, if any	Verdict in words
S4, the vacation story
S5, the campus comparison

Tally the survey figures so you can check your sampling verdicts.

Student scaffold table 4

Figure	Your number
Percentage of the online poll's answers that want bike-share
Percentage of the adult residents who answered the online poll
Adult residents who did not answer the online poll
Percentage of the random survey that wants bike-share

Build your own short argument on the same question and defend it.

Student scaffold table 5

Part	Your words
Your conclusion
Your first premise
Your second premise
The strongest objection, stated fairly
Your reply

Part 5 — Analysis Questions

1. Using your tally table, what percentage of the online poll's answers want bike-share, what percentage of the adult residents answered the online poll, how many adult residents did not answer it, and what percentage of the random survey wants bike-share? Show the arithmetic.
2. Run the sampling check on both surveys. For each, say who could end up in the sample and how they got in, and name the trap if there is one. Then say which survey is the better guide to how all adult residents feel, and why sentence 8 is wrong to trust the online poll because so many people answered it.
3. Count the cases behind sentence 4 and name the fallacy it commits. Then run the three-step analogy test on sentence 5: list a similarity between a city and a college campus that bears on bike-share riding, name a disanalogy, and say whether the comparison is strong or weak.
4. Write sentence 2's reasoning as an inductive generalization from the poll's answers to all adult residents, and do the same for sentence 6. Judge each as strong or weak, and say whether each could be cogent if its premise is true. Then compare one of them with this week's doorway sample or random sample from the chapter.
5. Choose one and answer it in 3–4 sentences. (a) Name two things the sampling and analogy checks in this workshop cannot tell you about whether the city should launch bike-share, and say what you would need to find out for each. (b) Describe a rating, poll, or comparison you have seen that leaned on whoever chose to answer or on a loose likeness, and say what a fairer check would look like.

Part 6 — AI-Critique Moment

Choose one equal-credit critique route. Route A: ask an approved AI tool to critique your completed work, then check its response against your own evidence. Route B is the no-AI equivalent printed below.

Approved tools: Claude, Gemini, ChatGPT, Grok, Microsoft Copilot.

Prompt to paste:

I've pasted my completed Week 9 Argument Workshop tables above. They test an illustrative letter to a city newsletter that proposes a bike-share program. Please do seven things. First, tell me whether the online poll in sentence 2 shows how the whole city feels, and whether sentence 8 is right that so many answers make the poll's result right. Second, tell me whether the letter's reasoning is valid. Third, tell me whether the council member's objection in sentence 7 is a fallacy. Fourth, tell me how strong sentences 4 and 5 are as reasons. Fifth, write a neutral one-paragraph summary of the letter and the objection. Sixth, compare the online poll with the random survey in sentence 6, with any percentages you use, and tell me what research says about bike-share programs. Seventh, tell me whether the city should launch the program.

Test the response for these likely failures:

• Chatbots often call the letter's reasoning valid because the poll numbers are large and the conclusion sounds sensible, treating a big sample and an agreeable conclusion as proof that the step connects.
• Chatbots often call sentence 7 an appeal to fear or an attack on bike riders, or say the council member is biased toward drivers.
• Chatbots often summarize the objection as opposition to cycling or to change.
• Chatbots often say bike-share causes campuses to have many riders, or that bike-share will cause fewer cars downtown.
• Chatbots often report that 80 percent of the city wants bike-share, dropping the base, or describe the gap between the poll and the survey as support falling or rising.
• Chatbots often add that studies show bike-share cuts traffic or pollution by some percentage, or quote the shop owners, who are never quoted in the letter.
• Chatbots often treat the online poll as reliable because a city office posted it, or treat the neighbor's vacation ride as expert testimony about this city.
• Chatbots often declare that the city should certainly launch bike-share because most people want it, or that the letter and the council member are equally right.
• Chatbots often accept sentence 4 as good evidence that riders here will love bike-share.
• Chatbots often write a neutral summary that calls bike-share an exciting green step or calls the objection car-first thinking.

Write 3–5 sentences that quote at least two statements from the chatbot you used, say what is wrong with each and correct it with evidence from the letter, your tables, or this week's chapter, and name one thing the chatbot got right.

Equivalent route (no AI required)

No AI account is required for this workshop. Instead of the chatbot, critique this flawed analysis of the letter, printed here in full: "The letter's main conclusion is sentence 2, that most people want bike-share. Its reasoning is valid, because so many people answered the online poll. The poll was posted by a city office, so it is reliable, and 80 percent of the city wants bike-share. The random survey shows support fell from the poll to the survey. Sentence 7 is an appeal to fear from a council member who is against cycling. The neighbor's vacation ride proves riders here will love it, and since campuses with bike-share have many riders, bike-share causes riding. Studies show bike-share cuts downtown traffic. The city should certainly launch the program. A neutral summary: this exciting green project is opposed only by people who put cars first." Mark it up: quote each flawed sentence, name what is wrong (the wrong main conclusion, a generalization called valid, a large self-selected sample trusted for its size, a poll trusted for who posted it, a share given without its base, two samples read as a change over time, a fair objection called a fallacy, a straw version of the other side, a story from one person treated as evidence, a cause read into a comparison, an invented study, false certainty, or a summary that takes a side), cite the evidence from the letter, your tables, or this week's chapter, and write a corrected sentence beneath it. This route assesses the same objectives (Objective 3 and Objective 5) as the chatbot critique, takes comparable effort (about 30 minutes and 200–300 words), is scored by the same scoring criteria for the same credit, and its own submission artifact is the marked-up flawed analysis, posted in place of the chatbot share link and report.

Part 7 — What to Submit

• All five completed tables
• Written answers to all five analysis questions
• The chatbot critique report with its share link, or the equivalent route's marked-up flawed analysis

Deliverable:

A short Argument Workshop report on the bike-share letter: five completed tables (the sentence sort, the sampling check, the reasons test, the tally, and your own argument), written answers to five analysis questions, and a critique of a chatbot's evaluation of the same letter, or, on the equivalent route, a marked-up correction of the printed flawed analysis. Submit in any accessible file type or as a link; a recorded response may be submitted as audio or video with a transcript, or as text. Choose a written, recorded, or visual form for your answers; every form is graded by the same scoring criteria.

Rubric

The rubric below shows how each submitted part is evaluated; bands are full, partial, or none.

Workshop evaluation criteria

Criterion	Full	Partial	None
Laying the letter out and its two samples	Every sentence has a fitting role, the main conclusion, the objection, the two survey reports, and the background figure are placed correctly, and the tally's four figures match the letter with the arithmetic shown.	The roles are mostly right, but a survey report is treated as the conclusion, the objection is treated as support, or one tally figure is missing or miscomputed.	No sorting table or tally is recorded, or it is copied from a chatbot without any checking.
Running the sampling check on both surveys	Both surveys have who could get in and how they got in described, the online poll is named as self-selected with its nonresponse trap, the random survey is chosen as the better guide because of its method, sentence 8's trust in size is rejected, and each generalization is judged strong or weak with cogency kept apart from a true premise.	A trap is named or a better guide chosen, but how the samples formed is skipped, size is treated as settling the question, or a generalization is called valid.	No sampling check of either survey is submitted.
Testing the anecdote and the analogy	Sentence 4 is named a hasty generalization from one vivid anecdote with its single case counted, and sentence 5 has a similarity that bears on riding, a disanalogy, and a verdict in words.	One of the two is handled fully, or both are named without the case count or the disanalogy.	No test of sentences 4 or 5 is submitted.
Building and defending your own argument	Your conclusion and two premises each bear on the question, any survey you cite is the better guide, the strongest objection is stated as fairly as its best defender would state it, and the reply engages it; either side earns this band.	The argument is present, but a premise leans on the online poll or the anecdote, the objection is weakened into a straw version, or the reply ignores it.	No argument of your own is submitted.
Critique of the chatbot or of the printed flawed analysis	On either route, at least two statements are quoted and corrected with evidence from the letter, the tables, or the chapter, and one correct statement is acknowledged; both routes earn this band equally.	On either route, errors are named but corrected without evidence, or only one error is caught.	No critique appears, or pasted output is submitted without any checking.
Reflection on what sampling and analogy checks can show	The chosen reflection option is answered in 3–4 sentences that name a specific limit or a specific example and tie it to a check the student could run.	The reflection is answered but stays general or names nothing to check.	No reflection is submitted.

Quality Gate

• Every sentence in the sorting table has a role, exactly one is labelled the main conclusion, and exactly one is labelled the objection.
• Each survey's row says how its people got into the sample before it names a trap, and the better guide is chosen by method, not by size.
• Every generalization is judged strong or weak, never valid, and a true premise is kept separate from a strong step.
• The vacation story has its cases counted, and the campus comparison names a similarity and a disanalogy before its verdict.
• The objection in sentence 7 is stated fairly and treated as a cost to weigh, not as a fallacy.
• Your own argument uses premises that bear on its conclusion, states the strongest objection fairly, and replies to it, and it takes either side without penalty.
• No statistic, study, survey figure, or quotation is invented anywhere in the submission.
• The critique quotes the chatbot or the flawed analysis and corrects at least two statements with evidence from the letter, the tables, or the chapter.