Hi Brigid,
I'm not an iframe expert, but I found a WebAIM iframes article that includes a couple more considerations for embedding. I wouldn't ask students to interact with information on the page and in the tutorial, precisely for the split attention affect you mention, but that should address issues with screen reader users going back and forth (at least to my understanding). Screen reader users will still need to navigate the question pane and the provided page- but there's not a whole lot to be done about that, if the content you're trying to provide requires consulting another page.
Can you say more about the new window violating accessibility guidelines? I try to avoid new windows when I can, but there are some cases where they are needed and as I understand it, acceptable as long as they are labeled. It can also be helpful to offer a link to the tutorial so that users who would prefer not to navigate the embedded tutorial can view it in it's own window.
I like LibWizard tutorials for being able to show a page side by side with the questions, but I do think they are not ideal for many other types of information display. Thanks for asking!
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Anaya Jones She/Her/Hers
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Accessibility & Online Learning Librarian
Northeastern University
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