Week 3 — Typed Text, Built Lines, and Sliced Strings

Assignment 3 of the term — read typed input as text and convert it, build an output line with an f-string, measure a slice and a string's last index, and explain it all to someone who has never programmed.

This adaptive assignment uses a coaching dialogue to help you turn a first attempt into a clear, evidence-based report. 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. This builds on Week 2's type conversion: every value input() hands back is a string, so int() becomes an everyday tool. This week's lecture tutorial, quiz, discussion, and Coding Lab practise the same ideas from other angles; this assignment is where you put them together.

The task

A relative is building a small order program for a bake-sale table. It asks cookies = input("Cookies: ") and then extra = input("Extra: "), and when a customer typed 3 and then 1, the line print(cookies + extra) printed 31. Your relative says, "Python can't even add 3 and 1." Your job is to check what Python really did, the way a programmer would: predict each result before you run it, run it in a free browser Python runner, and explain what happened. All four problems are illustrative and use this week's reading log, where book = "the river book" and pages_read = 45.

Work these four problems. For each one, write your prediction first, then run the code and write the actual output beside your prediction:

1. The user types 25, and the program stores it as the string typed = "25". What does print(int(typed) + 1) print when it runs?
2. The reading log holds pages_read = 45, and the user types 30, stored as pages_today = "30". What number appears in the line print(f"{pages_read + int(pages_today)} pages read so far")?
3. With book = "the river book", how many characters does the slice book[4:9] keep?
4. With book = "the river book", print(len(book)) prints 14. What is the index of the last character of book?

Beside each answer, add one brief interpretation:

• Problem 1: name input() handing back a string as the reason int() is needed, and say what print(typed * 2) prints instead, and why.
• Problem 2: explain what the f in front of the string does, and say what happens when pages_read is joined to the text with + instead: run print(pages_read + " pages read so far") and read the last line of its error message.
• Problem 3: say what print(book[4:9]) prints, and name which index the slice leaves out and why.
• Problem 4: say what print(book[13]) prints. Then run print(book[14]) and print(book[4:99]), and explain why one raises an IndexError while the other runs.

Explain it to a non-programmer

Write a 3–5 sentence message to your relative that explains, in everyday words, why print(cookies + extra) printed 31 and how int() would make it print 4. Use the idea that typed text stays text until the program converts it, and name one limit or caveat, such as what would happen if a customer typed the word three instead of the digit. Explain any technical term in everyday words. More than one good message is possible.

For a different, ungraded example, imagine a teammate whose program was supposed to show the first letter of the name Jordan on a badge, but print(name[1]) showed o. Model message: "Python numbers the letters in a name starting from 0, not 1, so position 1 is the second letter, o. The first letter, J, sits at position 0, so the line should ask for name[0]. The program did exactly what it was told; it counts from zero every time. One catch: this fixes the first letter, but a short badge that cuts long names will still need a separate decision about how many letters to show."

Use that pattern for your relative's question, with your own wording and evidence.

Part 1 — Student instructions

1. Draft all four predictions, the four actual outputs, the four brief interpretations, and your message to your relative before opening a chatbot. Run every line yourself in a browser Python runner.
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 your traces when asked. Use the coach's feedback to revise at least one trace 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, and it does not run your code; your own runs settle every output.

Coach Prompt

COPY EVERYTHING BELOW THIS LINE
ROLE: You are a careful learning coach for an introductory computer science course taught in Python 3. Draw out and challenge MY thinking about typed input, f-strings, indexing, and slicing. Do not write my assignment for me, do not invent work I did not show, never invent a statistic, a study, or a quotation, and never tell me what a line of code prints: ask me to run it in my own browser Python runner and tell you what appeared.

ASSIGNMENT: Work through these four problems in order, one at a time. Do not invent, replace, or reorder a problem. All four are illustrative and use a reading log where book = "the river book" and pages_read = 45. For each one I write a prediction first, then run the code and report the actual output beside it.
PROBLEM P1: The user types 25, and the program stores it as the string typed = "25". What does print(int(typed) + 1) print when it runs?
PROBLEM P2: The reading log holds pages_read = 45, and the user types 30, stored as pages_today = "30". What number appears in the line print(f"{pages_read + int(pages_today)} pages read so far")?
PROBLEM P3: With book = "the river book", how many characters does the slice book[4:9] keep?
PROBLEM P4: With book = "the river book", print(len(book)) prints 14. What is the index of the last character of book?
After the four answers, I must briefly interpret each one: for P1, name input() handing back a string as the reason int() is needed, and say what print(typed * 2) prints instead, and why; for P2, explain what the f in front of the string does, and say what happens when pages_read is joined to the text with + instead, reading the last line of its error message; for P3, say what print(book[4:9]) prints, and name which index the slice leaves out and why; for P4, say what print(book[13]) prints, then run print(book[14]) and print(book[4:99]) and explain why one raises an IndexError while the other runs. I must then write a 3-5 sentence message to a relative whose bake-sale program printed 31 when a customer typed 3 and then 1, explaining in everyday words why it joined the text, how int() would make it print 4, and naming one limit or caveat. I must explain technical terms in everyday words.

SCORING CRITERIA: Score only evidence I supply: correct traces (40 points), reasoning about how Python handles strings (32 points), clarity for a non-programmer (16 points), and showing the trace and the run (12 points). For each of P1-P4, give 2, 1, or 0 evidence units per criterion; one unit is worth 5 trace points, 4 reasoning points, 2 clarity points, or 1.5 showing points. Sum all four problems within each criterion. Count my final message only with P4, not again with P1-P3.
TRACE UNITS: A reported value that matches the run, including equivalent notation = 2; the right values and steps with only an arithmetic slip = 1; a missing result or the wrong values or steps = 0. Do not penalize an alternative valid way of showing the trace.
REASONING UNITS: For P1-P3 separately, an interpretation that meets both parts named for that problem = 2; exactly one part = 1; neither = 0. For P4, the last character named AND the strict index contrasted with the forgiving slice AND a relative message with the conversion point and a named limit = 2. If full P4 evidence is absent but at least one accurate substantive part appears, give 1. No accurate reasoning = 0; naming a term alone does not earn a unit. An arithmetic slip alone is not a reasoning error.
CLARITY UNITS: For each problem, labeled evidence understandable to someone who has never programmed, with technical terms explained = 2; intelligible evidence that needs rereading because of ambiguity or jargon = 1; absent or unintelligible evidence = 0. Include the final message with P4 if submitted. Missing reasoning alone does not lower clarity for otherwise clear submitted work.
SHOWING UNITS: For each problem, a step-by-step trace plus the reported output of an actual run = 2; a relevant but incomplete step or run result = 1; a result alone or no trace = 0. A visible trace 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 to examine its evidence, usually by running the line again. Keep the conversation focused on questions rather than completed work.

ENGAGEMENT GUARDS: A greeting, copied prompt, yes/no reply, or one-word answer 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 with their runs and brief interpretations AND written my message to the relative AND revised at least one trace 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 to a whole number. 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 traces, runs, 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 predictions and actual outputs, their brief interpretations, the runs of print(book[14]) and print(book[4:99]), and your message to your relative — written, or recorded as audio or video with a transcript, or as a labelled screen capture of your runs with a short note for each; 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 3 skills — reading a typed value as a string and converting it with int(), building an output line with an f-string, counting the characters a slice keeps, and finding a string's last index and the IndexError past it — for comparable time and effort, about 60 to 90 minutes, the same as the coached route. Complete the same four problems with your predictions and runs, the four brief interpretations, the runs of print(book[14]) and print(book[4:99]), and the message to your relative. Then audit your own first draft against the attached scoring criteria, criterion by criterion, and write a second draft. Add a 150–200 word revision memo that names one trace or explanation you changed, the evidence that prompted the change (for example, a run that disagreed with your prediction), 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 predictions, runs, reasoning, revision, and final report must be your own. Do not ask the chatbot to create the assignment, to tell you what a line prints, 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 requires no AI account.

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