# Python list totals: observed generation results

Date: 2026-10-16. Environment: TutorFlow development classroom, English content.
This is one reproducibility check, not a production benchmark or a fixed price.
The PDF and PPTX in this folder are instructor-authored inputs. The excerpts below
come from the generated lesson and test. Review notes and example answers are
editor additions. No learner submissions or customer data are included.

## PDF to course

Input: python-list-totals.pdf, five pages.
Options: Build from materials; one syllabus file; adult beginners; one week;
one coding lesson; three quiz questions; short content. Assignments, chapter
slide drafts, and exams were turned off.

The analysis summary identified running totals, empty and negative-value lists,
the misplaced reset, and the supplied review answers. The first lesson attempt
returned to the setup screen without a completed saved body. One retry produced
a lesson and three quizzes. Reopening the lesson preserved that content.

### Generated practice code

```python
# Change numbers to [], [-2, 5], or [4] to test other inputs.
numbers = [3, 5, 2]
total = 0

for number in numbers:
    total = total + number

print(total)
```

The Run button returned `10` in the browser. The generated explanation also
covered `[] -> 0`, `[-2, 5] -> 3`, and `[4] -> 4`, and showed why resetting the
total inside the loop prints `2` for `[3, 5, 2]`. Those edge-case values were
checked independently in Python; only the default input was run in the product UI.
The screenshot `course-result.png` shows the generated lesson and browser output.

The course title was changed to identify the validation run. The generated
lesson text and code were not rewritten. Its three quizzes covered intermediate
running totals, the term initialization, and empty-list output when print is
inside the loop. This differs from the exact review-question wording in the source.

## PPTX to standalone test

Input: python-list-totals.pptx, five slides. The UI reported analysis complete
for five pages and displayed extracted source text.
Options: adult beginners; medium difficulty; English; four open-ended questions;
assessment after the lesson. The question count control initially showed 20,
even though the prompt requested four, so it was changed before generation.

### Generated question topics and explanations

1. **Tracing a Running Total.** Trace `[3, 5, 2]`. Generated explanation:
   "The totals after the three iterations are 3, 8, and 10, so the code prints 10.
   Each iteration adds the current list value to the total preserved from the previous iteration."
2. **Fixing the Misplaced Total Reset.** Explain why the buggy code prints `2`
   and move `total = 0` before the loop. The generated explanation correctly
   described how resetting inside the loop discards earlier additions.
3. **Comparing Empty and Single-Value Lists.** Compare `[]` and `[4]`. The generated
   explanation gave outputs `0` and `4`, with zero and one loop iterations.
4. **Adding Negative and Positive Values.** Write a loop for `[-2, 5]` without
   `sum()`. The generated explanation included a correct loop and the trace
   `0 -> -2 -> 3`.

### Review edits

The four generated explanations matched the source. However, the separate
Example Answer fields were empty. An editor filled all four fields from the
checked explanations. The generated question text described three-point rubrics,
but the score dialog showed zero for each question and a total-score target of
100. An editor set each question to 3 points, total 12, and the passing score to 10.
These are review corrections, not claims that the initial output was ready to share.

Editor-added example answer for the final question:

```python
numbers = [-2, 5]
total = 0
for number in numbers:
    total = total + number
print(total)
```

The totals are -2 and then 3. The program prints 3. Adding -2 decreases the total by 2.

## Observed credit balance

| Checkpoint | Displayed balance | Change since prior checkpoint |
| --- | ---: | ---: |
| Before PDF analysis and course setup | 4,533 | n/a |
| Course plan created | 4,530 | -3 |
| Lesson completed after one retry | 4,527 | -3 |
| PPTX test completed | 4,523 | -4 |

The displayed reduction was 10 credits across the run. These are UI balance
observations, not an itemized billing audit. The test tab had a stale balance
until generation completed. We did not separately attribute file analysis,
quiz generation, or the failed attempt. Check current pricing and your own
workspace usage history; another input or retry may cost differently.

## Limits of this check

This run used small text-based files and one development classroom. It did not
validate scanned PDFs, complex diagrams, long documents, all question types,
production performance, automatic grading, or PDF/PPTX export quality.
Generated outputs vary between runs. No visibility uplift or AI citation rate
has been measured from this change.