A Companion Video Indexed to the Section and the Answer Key

The short answer: A book can gain a visual explanation exactly where readers get stuck. Golpo turns the section and its verified solution into a narrated, illustrated companion, so a publisher or course creator can cover a chapter without a production crew.

Why this is practical now: Each problem can have a finished video. The author can narrate it, or an authorized clone can keep their voice across the book. A selfie puts a teacher beside the worked example.

Golpo plans the sequence, draws the steps, syncs the narration, and returns a polished companion. The frame editor can correct a label. One person can build chapter-level coverage.

Use the full Golpo production system

Golpo is built to be the world's best AI whiteboard explainer video maker. Give it a topic, a prompt, a script, an audio recording, or a source document. It scripts, plans the scenes, designs the visuals, narrates, times and synchronizes every frame, and returns a polished video. One person can run that system across a whole course.

For textbook companions, the page and answer key remain canonical. Golpo can plan and illustrate the explanation, the author can narrate it, and frame editing can correct a label without changing the approved teaching sequence.

• Start with an idea or source. Golpo can draft the script and plan the scenes from a topic, a document, or your outline. Script Mode can also speak the exact words you already trust.
• Keep the creator present. With AI Presenter, a course creator, founder, professor, or YouTuber can upload a selfie and appear beside the whiteboard. One person can lead a large lesson library without recording every visual sequence on camera.
• Use the right voice. Own Narration turns uploaded or live-recorded audio into the visual lesson. An authorized Voice Clone gives recurring lessons a recognizable voice at scale. Consent and pronunciation review remain required.
• Repair instead of restarting. The frame-by-frame editor can replace text, images, references, or an individual visual when the QA pass finds a local problem.
• Automate at scale. The Golpo API can be called from Codex, Claude Code, or through the Golpo MCP server in Cursor, VS Code with GitHub Copilot, Claude Code, Claude Desktop, and Visual Studio. The course platform can generate, poll, review, and publish without a person moving files between tools.

Beside the course’s own writing, or beside a book

The written-lesson spoke is for a paragraph the course itself published. The paragraph is canonical there. Here the canonical object is a section and a key the course does not fully control. Training PDFs are internal documents the organization owns. A workbook from a publisher is neither of those. The rights check is the first field in the record, before any script.

Walkthrough technique, once the item is legally usable, can follow the blank-page spoke. This page adds the index and the ban on pasting the publisher’s stem into a third-party tool.

The index

• Book title, edition, ISBN or URL, and the license.
• Section identifier as printed, so a student can find it.
• Problem number and part, as printed, when the course has the right to refer to that problem. When it does not, the record says “original parallel” and does not quote the copyrighted stem.
• The key the video will teach, recomputed, plus the page or file where the course’s key lives.
• Credit line when the source requires one. OpenStax’s CC BY terms, for the edition in use, belong in the record and on the page. Confirm the license on the edition you actually assigned. Do not assume every open book uses the same terms.
• Script hash and video status. A new edition of the book retires the companions that cited the old problem numbers.

The practical writing rule: invent a parallel item that practices the same skill, solve it, and point the student at the book’s problem as homework they do on paper. The video then says “this is the course’s parallel to section 3, problem 4” only if saying the number does not require reproducing the publisher’s expression. When in doubt, omit the publisher’s numbers and keep the skill. The pilots below use a constructed index so the guide itself is not borrowing a stem.

Problem 4, part b, answer 49

Constructed parallel: (5 + 2)². The sum inside is 7, and 7² = 49. The long form is 5² + 2 × 5 × 2 + 2² = 25 + 20 + 4 = 49. The shortcut that adds 25 + 4 = 29 drops the middle term, the same class of error as the Explain This expansion. The key is 49. The QA agent computes 49 and 29. A script that calls 29 the answer fails. A script that shows 29 as the dropped-middle-term error, clearly labeled, can pass. The index fields in the record are what let a page say “watch the parallel to part b” without pasting a publisher’s polynomial into the generate call.

Three-fourths of 20

Constructed parallel: 3 / 4 = x / 20. Then 4x = 60 is one path, and x = 15. The scale path: 4 × 5 = 20, so the numerator scales by 5 as well, 3 × 5 = 15. The decimal path: 0.75 × 20 = 15. Three paths, one key. The QA agent should produce 15 three times. If the course’s printed key said 12, the video does not “fix” the key in secret. The instructor resolves the disagreement, the key file changes or the script changes, and the hash updates. Students should not see a video that quietly contradicts the key the homework grader uses.

Both pilots are Script Mode renders of those originals. The hub’s watch-back looks for 49 versus 29 and for 15 versus a half-finished proportion.

Own Narration: OFF · Script Mode: ON · Duration: 1 minute · Orientation: Horizontal (16:9) · Style: Dry Erase · Color: ON · Language: English · Voice: Female 1 · Pace: Normal · Music: None

Problem four, part b, in the workbook section this video accompanies. The key says forty nine. Compute the quantity five plus two, squared. Five plus two is seven. Seven squared is forty nine. The long form uses the same square. Five squared is twenty five. The cross term is two times five times two, which is twenty. Two squared is four. Twenty five plus twenty plus four is forty nine. The shortcut that adds twenty five and four and skips the cross term gets twenty nine. Twenty nine does not equal seven squared. The index stores the book, the section, the problem number, and the agreement with the key. Forty nine agrees. Twenty nine is the step this companion is there to catch. Show forty nine from both the short square and the long sum. Twenty nine stays in the frame as the step that disagrees with the key.

Problem four, part b. Seven squared is forty nine. The long sum is twenty five plus twenty plus four. The shortcut that skips the cross term is twenty nine. End with forty nine marked as the key and twenty nine marked as the miss. Allowed labels: Problem 4 part b; (5 + 2)^2 = 49; 7^2 = 49; 25 + 20 + 4 = 49; Shortcut 25 + 4 = 29; Key 49. Do not add a sample stamp, a demo label, or any claim that the lesson is fictional. Show only the labels listed. If a number appears, it must match the narration exactly. No extra dates, prices, percentages, logos, or quotations.

Workbook teacher. Forty nine and twenty nine must not be blurred.

Own Narration: OFF · Script Mode: ON · Duration: 1 minute · Orientation: Horizontal (16:9) · Style: Dry Erase · Color: ON · Language: English · Voice: Male 1 · Pace: Normal · Music: None

Three fourths of twenty is the next numbered item. Write the proportion. Three over four equals x over twenty. Four times five is twenty, so the same multiplier on the numerator is three times five, which is fifteen. x equals fifteen. A second path uses the decimal. Three fourths is zero point seven five. Zero point seven five times twenty is fifteen. Both paths land on fifteen, and fifteen agrees with the answer key. Index the video to this problem number, not to a neighboring item. The book, the section, and the key stay in the record. The picture shows twenty, three fourths, and fifteen. A frame that shows another product does not match the key, and it does not ship with this problem. Fifteen has to be the last number standing. The proportion and the decimal both have to show fifteen. That is the key for this item.

A proportion and a decimal. Both reach fifteen. The video is indexed to this problem. End with fifteen as the only result left on the page. Allowed labels: 3/4 = x/20; 4 x 5 = 20; 3 x 5 = 15; x = 15; 0.75 x 20 = 15. Do not add a sample stamp, a demo label, or any claim that the lesson is fictional. Show only the labels listed. If a number appears, it must match the narration exactly. No extra dates, prices, percentages, logos, or quotations.

Two paths, one answer. Land on fifteen twice.

Edition changes

Publishers reorder problem numbers. A companion indexed to “section 3, problem 4” in the third edition can point at a different skill in the fourth. The platform stores the edition on the row. When the bookstore switches editions, those rows retire in bulk. The creator agent may draft new parallels. It may not retarget the old file by editing a title. The file’s pictures still show the old problem.

OpenStax updates are a milder version of the same habit. Even when the license allows adaptation, the credit and the section URL can change. The reviewer checks the current attribution requirements when the edition changes, not only when the course first adopts the book.

Risks

The serious risk is copyright, not arithmetic. A QA agent that checks 7² = 49 will not notice that the stem was copied from a commercial solution manual. The rights field is a human field. Uncertain rights block generate. “We only used a short excerpt” is a legal question this guide does not answer. The operational rule here is simpler: write an original parallel, or use a source whose license the course has read.

The second risk is key drift. Homework systems update answers. The video’s hash has to be compared to the key the grader uses this week. A termly diff between key file and script numerals is a reasonable calendar. A course that never diffs will eventually assign a video with last year’s answer.

A rights decision before any arithmetic

Staff need a short decision path that ends in generate or in a stop, and the arithmetic is not on that path until the end. First question: does the course own the stem, or is the stem an original parallel written by the course? If yes, continue. Second: is the stem from a book whose license the course has read, such as an OpenStax edition under the CC BY terms printed in that edition? If yes, store the required credit and continue. Third: is the stem a commercial problem, a teacher-edition solution, or a scanned page? If yes, stop. Do not paste it “just to draft.” The creator agent does not get a copy of a stem the rights field rejected. People are tempted to paste first and decide later because the draft feels productive. The record should make a rejected rights field disable the draft button.

When the path says continue, the key work begins. For the constructed square, the agent computes 49 and also computes the incomplete 29 so it can recognize the error if the script promotes it. For the proportion, the agent computes 15 three ways. Then a person compares those values to the key the grader will use. Agreement means a script may be drafted. Disagreement means the instructor edits the key or the stem, in the course’s own materials, and the hashes change. Nobody renders a “correction” that makes the video smarter than the homework key. Students experience that as the course contradicting itself, and they are right.

Edition rollover is a batch job with a human gate. The bookstore’s new edition list arrives. Every companion row citing the old edition is set to retired, in one action the instructor can see as a count before confirming. New parallels are drafted only for sections still in the syllabus. A section the new syllabus dropped does not get a new video “because the file already exists.” Existing files of dropped sections stay retired. Students on the new syllabus who open a direct link to an old companion should see a retired notice and a pointer to the current section, not the old explanation presented as current.

Write the parallel item’s stem in the course’s own words and keep a diff against the book if a reviewer is worried the parallel is too close. For these pilots the stems are (5 + 2) squared and the proportion 3/4 = x/20. They practice a square of a sum and a one-step proportion. They do not need a story problem, a character, or a setting copied from a chapter. If a writer adds a narrative that mirrors a commercial word problem, the rights field goes back to uncertain even though the numbers are original. Uncertain rights block generate. The key for the square remains 49, with 29 stored only as the labeled error. The key for the proportion remains 15. A workbook companion that cannot survive a side-by-side look at the book, because the sentence was lifted, should not be rescued by swapping one digit. Write a new stem.

Automate it: review gates and publishing with the Golpo API

For textbook companions, the whole path from source to published lesson can run as one pipeline on the course platform. An agent in Codex with the Golpo Codex Skill, in Claude Code with the Golpo Claude Skill, or in Cursor, VS Code with GitHub Copilot, Claude Code, Claude Desktop, or Visual Studio through the Golpo MCP server can call the Golpo API, wait for the render, and hand the file to the platform's review steps. Production stops being the limit on how many checked lessons a course can offer.

1. Attach the reference first. Store the textbook section and the workbook answer key with the lesson before any script is drafted.
2. Review the script against the reference before rendering. If a solution or source exists, the platform's QA agent checks the draft against it: it re-solves, re-adds, or re-reads, then compares. A mismatch or an uncertain result stops the job before Golpo renders anything.
3. Generate with Golpo. The agent sends the approved script in Script Mode, with the course's locked style, voice, Video Instructions, and Voice Instructions.
4. Transcribe what was actually said. Run speech-to-text on the finished video's audio. Learners hear the transcript, not the draft.
5. Run two independent transcript reviews. Make two separate LLM calls, separate from the creator agent and the QA agent. Each gets only the transcript and the reference, with no access to the draft or to the other reviewer's verdict. Each checks every spoken number, term, and claim, then returns pass or fail and quotes the line it objects to. The lesson moves on only when both pass. A failure or a disagreement goes to an instructor.
6. Check the frames. Pull a frame every few seconds and confirm every number and label on screen matches the approved script.
7. Publish. The pipeline posts the video to the course platform or LMS through its API as a draft, then releases it under the course's own approval rule.

FAQ

Can these lessons be generated and published automatically?

Yes, on the course platform's side. Using the Golpo MCP server or the Golpo Claude Skill, a pipeline can check the script against the textbook section and the workbook answer key, generate the video, run two independent transcript reviews, and post the lesson to the platform as a draft. Anything that fails a check goes to an instructor.

Can the prompt include the publisher’s problem statement?

Not unless the course has the rights to send that text to the tool and to display the result. The default on this page is an original parallel item. The index can still tell the student which skill the parallel practices.

What is (5 + 2) squared?

49. The long form is 25 + 20 + 4 = 49. The shortcut 25 + 4 = 29 drops the cross term. The constructed index calls this problem 4, part b, so the record has something to point at. It is not a commercial problem number.

What is three-fourths of 20?

15. From 3 / 4 = x / 20, x = 15. Also 3 × 5 = 15 because 4 × 5 = 20, and 0.75 × 20 = 15. The QA agent should agree across those paths.

How is this different from a video beside the course’s own paragraph?

There, the course’s paragraph is canonical and can be edited in place. Here, a book edition and a key the course may not control are canonical. Rights and edition go in the record first.

What credit does an OpenStax source need?

The credit its edition’s CC BY terms require, stored on the lesson and shown on the page. Confirm the edition you assigned. This guide does not paste OpenStax problems into the pilots.

Who resolves a disagreement with the printed key?

An instructor. The video stays unpublished while the key and the script disagree. The QA agent reports the mismatch. It does not pick a winner. Golpo does not see the item until a script is approved.

What happens when a new edition renumbers the problems?

Retire the old rows. Draft new parallels against the new edition. Do not retitle the old video and leave its pictures on the new problem number.

Related guides

• Checked lesson videos — the recomputation and the watch-back.
• Beside the written lesson — when the course’s own paragraph is the source.
• Training PDFs — documents the organization owns.
• Exercise walkthroughs — the step-by-step shape, once the item is usable.
• The learner’s wrong step — if the student submits 29 instead of 49.

Index the edition, write an original parallel, recompute the key, and retire the row when the book’s numbers move.