how to check a Canvas assignment for hidden text.

Canvas assignments and pages are written in the Rich Content Editor. It lets an instructor pick any text color and a font size, and switch to an HTML editor. Canvas's HTML allowlist keeps inline styles for color, font size, display, visibility, position, and opacity, so a sentence can be made white, shrunk to a speck, moved off the screen, or switched off entirely.

Reports of these traps rarely name the platform, but the method is the same on any web page. In 2024, a University of Oklahoma student found white-text instructions to mention Dua Lipa and Finland in an assignment after pasting it into Word. In 2026, an Alcorn State history professor hid the word Madagascar in white font in a midterm prompt, and 32 of his 35 students failed part of the midterm.

That last row matters. Text that is switched off never reaches a chatbot through copy and paste, so a trap meant to catch pasted prompts has to use one of the first three, and those are exactly the ones a screen reader reads aloud.

1. 01Select all
   Click in the assignment text and press Ctrl+A (Cmd+A on a Mac). White text shows up as highlighted lines in space that looked empty. Tiny or off-screen text can still stay out of sight, so do the next step too.
2. 02Paste it as plain text
   Copy, then paste into Notepad, or TextEdit in plain-text mode, or paste without formatting (Ctrl+Shift+V on Windows, Cmd+Option+Shift+V on a Mac). Color and size are stripped, so white, tiny, and off-screen text shows up as ordinary words. A normal paste into Word can keep white text white.
3. 03Compare with the page
   Read the pasted text against the assignment. A sentence that is in the paste but not on the page was hidden.
4. 04Look at the page code
   Right-click the assignment text and choose Inspect. The browser's Elements panel shows each piece of text with its style, including text that is switched off and never shows up in a copy.

You can also paste the copied assignment into Lervan's free hidden text checker. It flags sentences that address an AI, ask for a planted word, or try to override other instructions, and it counts invisible characters.

One limit to know: copied text loses its color and size, so the checker cannot tell which sentences were hidden on the page. It tells you which ones read like instructions for software. The comparison in the steps above tells you which ones were hidden.

Many assignments put the real instructions in an attached Word file or PDF. Download it from the assignment, or from Files, and check it the same way you would any document: hidden text in Word or hidden text in a PDF. A Word file gets the deepest check from the hidden text checker, because Word records how every run of text is styled.

Screen readers do not announce text color or size by default, so they read white and tiny text like any other sentence. A student who uses one hears a hidden instruction as part of the assignment, with no sign that it was meant to be invisible. Accessibility teams at the University of Oregon and the University of Chicago have both warned about this.

If you use a screen reader or text-to-speech and hear an instruction that seems out of place, such as a request to mention an unrelated name, ask your instructor before you follow it.

1. 01Do not follow it
   The visible assignment is your assignment. A hidden line addressed to a chatbot is not a requirement for you.
2. 02Keep a record
   Take a screenshot of the revealed text and note where it was on the page.
3. 03Ask if it changes the task
   If the hidden text could change what you are supposed to do, ask your instructor which instructions apply. Describe what you saw without guessing at intent.
4. 04Work within your course's AI policy
   A planted line usually means your instructor is checking for pasted AI answers. Write from the visible prompt and keep your drafts.

For what these lines usually say, see how to spot hidden AI prompts. For other file types, see how to find hidden text in any document.

The Rich Content Editor's Accessibility Checker flags text whose contrast with its background is below 4.5 to 1 (3 to 1 for large text), which includes white text on a white page. Before you publish a page with hidden text, remember who else reads it: screen-reader users hear it as part of the assignment, and students with custom color settings may see it.