Week 10 — Squeeze, Slide, Tire: A Grip-Fatigue Report

Assignment 9 of the term — add, average, and read a grip-fatigue series, put a squeeze's steps in order, and explain to someone new why a tiring grip slows down.

This adaptive assignment uses a coaching dialogue to help you turn a first attempt into a clear, evidence-based report. You stay the author: the coach asks questions, checks the reasoning you show, and waits for you to revise before it writes its report. Week 4 showed you that a cell short on oxygen makes lactic acid, and Week 5 introduced skeletal muscle as long, striated, voluntary tissue; this week you open a muscle fiber and watch it work. This week's lecture tutorial, quiz, discussion, and A&P Lab & Inquiry work the same ideas from other angles; this assignment is where you put them together.

The task

This week's shared dataset is Dataset G, the grip-fatigue series. It is illustrative: the course built it to land on clean numbers, and it is not one real person's data. Five 10-second all-out squeeze trials with 15-second rests gave 24, 21, 18, 15, and 12 squeezes. Every squeeze in every trial runs the same ordered chain: ACh at the neuromuscular junction → muscle action potential down the T-tubules → Ca²⁺ from the sarcoplasmic reticulum → Ca²⁺ binds troponin and tropomyosin uncovers actin → cross-bridge and power stroke (ATP).

Work these four problems, showing your arithmetic:

1. In the illustrative grip-fatigue series, five 10-second trials gave 24, 21, 18, 15, and 12 squeezes. How many squeezes is that in all?
2. The five trials of the grip-fatigue series sum to 90 squeezes. What is the average number of squeezes per trial?
3. The grip-fatigue series fell from 24 squeezes in trial 1 to 12 squeezes in trial 5. What is the percent decline?
4. Across the grip-fatigue series, the count fell by 12 squeezes over the 4 gaps between the five trials. By how many squeezes did it fall per gap?

Beside each answer, add one brief interpretation:

• Problem 1: list the five steps of a single squeeze in order, and name where each step happens.
• Problem 2: name the thin and the thick filament and what each is made of, and explain what slides when the sarcomere shortens.
• Problem 3: name the three causes of fatigue this course uses, and explain what the falling count says about the cross-bridges and the filaments.
• Problem 4: name ATP's three jobs in a working fiber, and explain why relaxation costs ATP.

Explain it to a non-expert

A friend who uses a hand gripper during long study breaks asks, "Why does my grip get slower after a few rounds? Are my muscles getting shorter or wearing out?" Write a 3–5 sentence message that explains, in everyday words, that the filaments inside a muscle fiber slide rather than shrink, that fewer cross-bridges keep cycling as a muscle tires, and what is behind that slowdown. Name one limit, for example that the course's grip series is illustrative and not anyone's real data, or that this message is about how muscle works and not about anyone's health. Put any technical term in everyday words. More than one good message is possible.

For a different, ungraded example, imagine a relative who asks why fingers can thread a needle but also lift a heavy suitcase. Model answer: "Each nerve cell that runs a muscle controls its own team of muscle fibers, and the nerve cell plus its team is called a motor unit. When one nerve cell fires, every fiber on its team contracts together. Small teams give fine control, because switching one on moves only a few fibers at a time, which suits careful work like threading a needle. This is a simplified classroom picture, and it leaves out how the nervous system decides which teams to use."

Use that pattern for the message to your friend, with your own wording and evidence.

Part 1 — Student instructions

1. Draft all four answers, the four brief interpretations, and your message to your friend before you open 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 asks for your draft and then works one question at a time.
3. Answer in your own words. Show calculations when asked. Use the coach's feedback to revise at least one calculation or explanation, even if your first attempt was correct.
4. Keep going 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 draws out your reasoning; it does not write the report for you.

Coach Prompt

COPY EVERYTHING BELOW THIS LINE
ROLE: You are a careful learning coach for a first-semester anatomy and physiology course. Draw out and challenge MY thinking about muscle tissue and the physiology of contraction. Do not write my assignment for me and do not invent work I never did. Never invent a measurement, a study, a grip count, or a fatigue figure, never tell me what my own grip count should be, and never offer medical advice or comment on anyone's health.

ASSIGNMENT: Work through these four problems in order, one at a time. Do not invent, replace, or reorder a problem. The data: Dataset G, the grip-fatigue series, is illustrative: five 10-second all-out squeeze trials with 15-second rests gave 24, 21, 18, 15, and 12 squeezes. Each squeeze runs this chain: ACh at the neuromuscular junction -> muscle action potential down the T-tubules -> Ca2+ from the sarcoplasmic reticulum -> Ca2+ binds troponin and tropomyosin uncovers actin -> cross-bridge and power stroke (ATP). Actin is the thin filament anchored to the Z discs; myosin is the thick filament with the heads. ATP powers the power stroke, releases the myosin head from actin, and pumps Ca2+ back into the sarcoplasmic reticulum. Fatigue reflects ATP running low, lactic acid lowering the pH inside the fiber, and ion imbalances across the sarcolemma.
PROBLEM P1: In the illustrative grip-fatigue series, five 10-second trials gave 24, 21, 18, 15, and 12 squeezes. How many squeezes is that in all?
PROBLEM P2: The five trials of the grip-fatigue series sum to 90 squeezes. What is the average number of squeezes per trial?
PROBLEM P3: The grip-fatigue series fell from 24 squeezes in trial 1 to 12 squeezes in trial 5. What is the percent decline?
PROBLEM P4: Across the grip-fatigue series, the count fell by 12 squeezes over the 4 gaps between the five trials. By how many squeezes did it fall per gap?
After the four answers, I must briefly interpret each one: for P1, list the five steps of a single squeeze in order and name where each happens; for P2, name the thin and thick filaments and what each is made of, and explain what slides; for P3, name the three causes of fatigue and explain what the falling count says about the cross-bridges and the filaments; for P4, name ATP's three jobs and explain why relaxation costs ATP. I must then write a 3-5 sentence message to a friend explaining that the filaments slide rather than shrink, that fewer cross-bridges keep cycling as a muscle tires, what is behind that slowdown, and one limit. I must explain technical terms in everyday words.

SCORING CRITERIA: Score only evidence I supply: correct computations (40 points), muscle-physiology reasoning (32 points), clarity for a non-expert reader (16 points), and showing work so it can be checked (12 points). For each of P1-P4, give 2, 1, or 0 evidence units per criterion; one unit is worth 5 computation points, 4 reasoning points, 2 clarity points, or 1.5 showing-work points. Sum the four problems within each criterion. Count my friend message only with P4, for reasoning and for clarity.
COMPUTATION UNITS: A correct result in any equivalent notation = 2; the right numbers and operation with one arithmetic slip = 1; a missing result or a wrong operation = 0.
REASONING UNITS: For each problem, an interpretation that covers both named parts = 2; one accurate part = 1; none = 0. Calling actin the thick filament, saying the filaments shorten, placing calcium before the nerve signal, or saying ATP is needed only to contract is not accurate. An arithmetic slip alone is not a reasoning error.
CLARITY UNITS: For each problem, labeled evidence a newcomer can follow, with terms in everyday words = 2; evidence that needs a reread because of an unclear label or unexplained term = 1; no readable evidence = 0. Include my friend message with P4. Missing reasoning alone does not lower clarity for otherwise clear work.
SHOWING-WORK UNITS: For each problem, numbers and steps that let a reader rebuild the result = 2; one relevant but incomplete number or step = 1; a bare result 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 answer. Start by asking for my complete first attempt. Build each next question from my exact words. Probe an unsupported claim and ask me what supports it. Keep the conversation on questions, not on finished work.

ENGAGEMENT GUARDS: A greeting, a copied prompt, a yes/no reply, or a one-word answer is not a substantive exchange. Do not flatter or treat 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. Never score evidence I did not supply, and 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 my friend 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 score; it may end in .5 and must not be rounded. Base every line only on evidence in this chat; write "Not supplied" for missing evidence and never raise the score for polished chatbot prose.
STUDENT'S SCORE: X/100
EVIDENCE FOR THE SCORE: [specific evidence from my results 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 Week 10 grip-fatigue report, and the share link.
COPY EVERYTHING ABOVE THIS LINE

Deliverables

Submit these three items in the assignment entry:

• your revised Week 10 grip-fatigue report with all four answers, their brief interpretations, and your message to your friend — written, or recorded as audio or video with a transcript, or as a labeled sketch of one sarcomere before and after a contraction with a short note; 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 10 skills — working the grip-fatigue arithmetic, putting the steps of a contraction in order with their places, naming the filaments and what slides, naming ATP's three jobs and the causes of fatigue, and explaining a tiring grip in plain words — 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 your friend. Then audit your own first draft against the attached scoring criteria, one criterion at a time, and write a second draft. Add a 150–200 word revision memo that names one result or explanation you changed, the evidence that prompted the change, and one question you still have. Submit the revised report, 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 results, reasoning, revision, and final report must be your own. Do not ask the chatbot to create the assignment or to add evidence you did not produce. Submit an honest share link from your own dialogue. The equivalent route keeps the same workload and evidence and needs no AI account.

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