What a DUMP!
Wait, 1st let's address why an infodump is a 'bad story' trope. It comes from TV/film where writers have been forced to bridge scenes that otherwise would make no sense, and usually because of production limitations, not because any writer wanted it that way.
And if the script is being re-written mid-production (which isn't unusual) it's a sign other disasters are happening on that production. They aren't making the script as it was originally written.
Is 'infodumping' the important parts of a story via an in-universe
lesson in school/documentary/the news/other educational medium bad
An infodump is a lot of (necessary) information, that has been rushed and/or inelegantly presented. It's only 'bad' when it's bad.
There's no excuse for an infodump in a novel, we can't blame the production. But really any bad scene is... just a bad scene. If it clunks it needs to be edited. If it works, it's justified no matter how trope-y or cliché. Sometimes it's the lesser evil.
It sounds like you aren't too worried about it, and it's not the first time you've used it. I'm sure you're good.
Here are some reasons why you might want to open with an in-world 'infodump'.
- It's the exact lesson the protagonist needs to learn (a bit on the nose, but essentially a setup with a payoff later)
- Worldbuilding, genre signaling
- Foreshadowing and tone
- It's false or naive (it will be subverted later)
- It's a fundamental tenet of this world (everyone already accepts this as gospel truth so: square one)
- It's THE central conflict (again, foundational to the story)
- voice of authority (not just information, but letting us know the person speaking is important and knowledgable)
- It's a Greek chorus (able to 'debate' the conflict through disparate voices, or represent society's voice that is counter to the protagonist)
- It's a stealth prolog (ostensibly we're meeting our characters in their 'normal', but we're being fed a LOT of information about how things got to be the way they are, which is not part of THIS story....
All of the above
Verhoven's Starship Troopers has a heck of an opening classroom infodump where naive students flirt, and debate a lecture about 'citizenship' (and how "democracy lead the world to chaos", and "voting is violence") from a gung-ho amputee veteran teacher –– the scene is subversively telling us they are a fascist society where citizens are disfigured in endless wars to 'earn' basic social rights (access to jobs, ability to vote, having children) – hard contrast to our own world values.
Since the characters never question their fascist perspective (even as it gets them slaughtered), this infodump scene establishes Verhoven is not celebrating war, but presenting a society distorted by galactic imperialism. The students don't seem to be aware they are at war, meanwhile their 'war hero' teachers display survivor bias and are patriotic about the sacrifices they've made.