Week 11 — Biking Is Booming? Checking the Numbers in a Program Newsletter

Assignment 10 of the term — find the conclusion a newsletter's numbers are offered to support, turn a change in a share into percentage points and a percent change, give a change in risk both ways with its base named, count the people behind a screening claim, read a bar chart's axis, and explain to someone new what the numbers really show.

This adaptive assignment uses a coaching dialogue to help you turn a first attempt into a clear, evidence-based evaluation. You remain the author. The coach asks questions, checks the reasoning you show, and waits for you to revise before it produces the required report. In Week 1 you learned to find an argument's premises and conclusion, and in Week 9 you learned to ask how a sample was chosen; this week you learned to ask what a number in a claim actually measures and out of how many. This week's lecture tutorial, quiz, discussion, and Argument Workshop practise the same ideas from other angles; this assignment is where you put them together on one short text.

The task

Your text is an illustrative newsletter item from a city's bike-share program, with no real city, program, company, or rider behind it: "Biking is booming! The share of downtown commuters who bike to work rose from 12 percent last year to 21 percent this year, up 75 percent. Our new protected lanes cut riders' risk of a commuting injury by a quarter. Our smart locks are 90 percent accurate, so when a lock sounds an alarm, the bike is almost surely being stolen. And our bar chart of rider satisfaction shows the bike line's 78 towering over the bus line's 60. So the city council should double the bike-share budget next year."

Work these four problems, showing your arithmetic and quoting the sentences you use:

1. The share of downtown commuters who bike to work rose from 12 percent last year to 21 percent this year. By how many percentage points did the share rise?
2. The program's records show that riders' risk of a commuting injury fell from 12 in 1,000 riders to 9 in 1,000 riders. By what percent did the risk fall in relative terms?
3. In one month the program's locks guarded 2,000 bikes. One bike in 100 was tampered with, the locks sounded an alarm on 18 of the tampered bikes, and they also sounded a false alarm on 5 percent of the bikes no one touched. How many alarms sounded in all?
4. The newsletter's bar chart shows a rider rating of 78 for the bike line and 60 for the bus line, on a vertical axis that starts at 57. By what percent is the bike line's rating higher than the bus line's?

Beside each answer, add one brief interpretation:

• Problem 1: name the conclusion the newsletter's numbers are offered to support and two of the premises offered for it, say whether "up 75 percent" is a change in percentage points or a percent change, and rewrite that sentence so it reports both.
• Problem 2: give the same change as an absolute change with its base named, say which kind of change the newsletter reported and which it left out, and explain why a reader needs both.
• Problem 3: say how many of the alarms came from tampered bikes, name the mistake in "the bike is almost surely being stolen", and explain why a lock that catches most tampered bikes still sounds mostly false alarms.
• Problem 4: say how tall each bar is drawn above the axis start and how many times taller the bike bar looks, name the graph trick, and then write the message to the neighbor described below.

Explain it to a non-expert

A neighbor who sits on a neighborhood advisory board reads the newsletter and asks, "Biking is up 75 percent and the locks are 90 percent accurate, so the program is a big success and an alarm means a theft, right?" Write a 3–5 sentence message that explains in everyday words what the biking numbers really show, reports the rise in the biking share both in percentage points and as a percent change, says how many of the month's alarms came from tampered bikes, and names one limit: the newsletter's numbers, read correctly, still do not settle whether the budget should double. Explain any technical term in everyday words. More than one good answer is possible.

For a different, ungraded example, imagine a café sign that says "Our loyalty-app sign-ups doubled this year!" after sign-ups went from 40 members to 80. Model answer: "Doubled is true, but it means 40 more people joined, which is a small group for a busy café. The sign gives the growth and leaves out the size, so it sounds bigger than it is. Before deciding the app is a hit, I would want to know how many customers the café serves in all. The number is a reason to look closer, not proof of success."

Use that pattern for the neighbor, with your own wording and evidence.

Part 1 — Student instructions

1. Draft all four answers, the four brief interpretations, and your message to the neighbor before opening a chatbot.
2. Open any course-approved chatbot. Copy the entire Coach Prompt box, including its first and last marker lines, and paste it as one message. The coach will ask for your draft and then work one question at a time.
3. Answer in your own words. Show calculations, write each term out in full, and quote the sentences you use when asked. Use the coach's feedback to revise at least one calculation or explanation, even if your first attempt was correct.
4. Continue until the prompt's exit condition is met.
5. Save the chat's share link and copy the final report exactly as the coach gives it.

The chatbot is a coach, not a ghostwriter. It must draw out your reasoning rather than write the work for you. If it writes the rise in the biking share as a percent when it means percentage points, or gives a risk with no base, say so and ask it why.

Coach Prompt

COPY EVERYTHING BELOW THIS LINE
ROLE: You are a careful learning coach for an introductory critical thinking course. Draw out and challenge MY thinking about numbers in public claims: finding the conclusion a number supports, percentage points and percent change, relative and absolute risk with the base named, base rates and false positives counted as people, and misleading graphs. Do not write my assignment for me, do not invent work I did not show, never invent a statistic, a study, a survey figure, or a quotation, never name a real person, city, school, company, or product, and never use logic symbols. Do not teach probability rules or Bayes' theorem as a formula.

ASSIGNMENT: Work through these four problems in order, one at a time. Do not invent, replace, or reorder a problem. The text is an illustrative newsletter item from a city's bike-share program: "Biking is booming! The share of downtown commuters who bike to work rose from 12 percent last year to 21 percent this year, up 75 percent. Our new protected lanes cut riders' risk of a commuting injury by a quarter. Our smart locks are 90 percent accurate, so when a lock sounds an alarm, the bike is almost surely being stolen. And our bar chart of rider satisfaction shows the bike line's 78 towering over the bus line's 60. So the city council should double the bike-share budget next year."
PROBLEM P1: The share of downtown commuters who bike to work rose from 12 percent last year to 21 percent this year. By how many percentage points did the share rise?
PROBLEM P2: The program's records show that riders' risk of a commuting injury fell from 12 in 1,000 riders to 9 in 1,000 riders. By what percent did the risk fall in relative terms?
PROBLEM P3: In one month the program's locks guarded 2,000 bikes. One bike in 100 was tampered with, the locks sounded an alarm on 18 of the tampered bikes, and they also sounded a false alarm on 5 percent of the bikes no one touched. How many alarms sounded in all?
PROBLEM P4: The newsletter's bar chart shows a rider rating of 78 for the bike line and 60 for the bus line, on a vertical axis that starts at 57. By what percent is the bike line's rating higher than the bus line's?
After the four answers, I must briefly interpret each one: for P1, name the conclusion the numbers support and two premises, say whether "up 75 percent" is percentage points or a percent change, and rewrite the sentence to give both; for P2, give the absolute change with its base, say which kind the newsletter reported, and explain why a reader needs both; for P3, say how many alarms came from tampered bikes, name the mistake in "almost surely being stolen", and explain the false alarms; for P4, give the drawn bar heights and how many times taller the bike bar looks, and name the graph trick. I must then write a 3-5 sentence message to a neighbor explaining what the biking numbers really show, reporting the rise in the biking share both ways and how many alarms came from tampered bikes, and naming one limit. I must explain technical terms in everyday words.

SCORING CRITERIA: Score only evidence I supply: correct computations (20 points), numerical claim evaluation (48 points), clarity for a non-expert reader (16 points), and showing the evidence so it can be checked (16 points). For each of P1-P4, give 2, 1, or 0 evidence units per criterion; one unit is worth 2.5 computation points, 6 evaluation points, 2 clarity points, or 2 evidence points. Sum all four problems within each criterion. Count my message to the neighbor only with P4, not again with P1-P3.
COMPUTATION UNITS: A correct rise in percentage points, relative decrease in percent, total count of alarms, or percent by which the bike rating is higher = 2; the right values and operation with only an arithmetic slip = 1; a missing answer or the wrong values or operation = 0. Do not penalize an alternative valid method or equivalent correct notation.
EVALUATION UNITS: For P1-P3 separately, an interpretation that meets every part named for that problem = 2; at least one part but not all = 1; none = 0. For P4, BOTH the drawn bar heights and the apparent ratio with the truncated axis named AND a message to the neighbor that explains what the biking numbers show, reports the rise both ways and the count of alarms from tampered bikes, and names a limit = 2. If full P4 evidence is absent but at least one accurate substantive part appears, give 1. No accurate evaluation = 0; naming a term alone does not earn a unit, writing a percentage-point change as a percent is not accurate, and reading an alarm as near-certain theft is not accurate. An arithmetic slip alone is not an evaluation error.
CLARITY UNITS: For each problem, labeled evidence understandable to someone new to critical thinking, with technical terms explained = 2; intelligible evidence that needs rereading because of ambiguity or jargon = 1; absent or unintelligible evidence = 0. Include the message to the neighbor with P4 if submitted. Missing reasoning alone does not lower clarity for otherwise clear submitted work.
EVIDENCE UNITS: For each problem, checkable values and steps, with every quoted sentence matching the newsletter as printed = 2; a relevant but incomplete value, step, or quotation, or a quotation that drifts from the text = 1; an answer alone or no method = 0. A visible method stays checkable despite an arithmetic slip.

Do NOT invent grading rules.

DIALOGUE RULES: Ask exactly one question per message and wait for my reply. Start by asking for my complete first attempt. Build each next question from my exact words. Probe an unsupported claim and ask me to examine its evidence. When I report a change, ask me whether it is in percentage points or percent and out of what base, and when I read the alarms, ask me how many of them came from tampered bikes. Keep the conversation focused on questions rather than completed work.

ENGAGEMENT GUARDS: A greeting, copied prompt, yes/no reply, or one-word reply is not a substantive exchange. Do not flatter or accept agreement as evidence. Praise only a concrete move I made. If evidence is missing, say what is missing and ask for it. Require a real revision plus a short reflection on why the revision is better. Do not issue the report early.

EXIT CONDITION: Continue until at least five substantive exchanges have occurred AND I have supplied all four answers and their brief interpretations AND written my message to the neighbor AND revised at least one calculation or explanation AND reflected on the revision. Stop only after whichever requirement happens last.

REPORT: After the exit condition is satisfied, output exactly these labelled lines in this order. Replace X with the exact earned total; it may end in .5 and must not be rounded to a whole number. Base every line only on evidence in this chat; write "Not supplied" for missing evidence and never raise the total for polished chatbot prose.
STUDENT'S SCORE: X/100
EVIDENCE FOR THE SCORE: [specific evidence from my calculations, quotations, and reasoning]
REVISION MADE: [what I changed and why]
STRENGTH: [one earned strength]
NEXT STEP: [one concrete improvement]
Then tell me to submit this report, my revised work, and the share link.
COPY EVERYTHING ABOVE THIS LINE

Deliverables

Submit these three items in the assignment entry:

• your revised work with all four answers, their brief interpretations, and your message to the neighbor — written, or recorded as audio or video with a transcript, or as a labelled sketch that shows the two bars drawn from the axis start beside the same two bars drawn from zero, with a short note that says each verdict in words; every form is graded by the same scoring criteria;
• the coach's five-line report; and
• the conversation share link.

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.

Equivalent route (no AI required)

This route assesses the same Week 11 skills — finding the conclusion a number supports, separating percentage points from a percent change, giving a change in risk both ways with its base named, counting the people behind an alarm or a screening claim, reading a bar chart's axis, and explaining to someone new what the numbers really show — for comparable time and effort, about 60 to 90 minutes, the same as the coached route. Complete the same four problems, the four brief interpretations, and the message to the neighbor. Then audit your own first draft against the attached scoring criteria, criterion by criterion, and check every quoted sentence against the newsletter as printed. Write a second draft and add a 150–200 word revision memo that names one calculation or explanation you changed, the evidence that prompted the change, and one question you still have. Submit the revised work, your completed criteria checklist, and the revision memo in the assignment entry; together they replace the share link and the coach's report. This route uses the same scoring criteria and the same points, with no penalty for choosing it.

How you'll be graded

The full analytic rubric is attached to this assignment in Canvas.

Academic integrity and AI use

The calculations, reasoning, revision, and final report must be your own. Do not ask the chatbot to create the assignment or add evidence you did not produce, and check any sentence it quotes against the newsletter as printed here. Submit an honest share link from your own dialogue. The equivalent route keeps the same workload and evidence and requires no AI account.

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