There are already some comments complimenting this post, but I wanna amplify the choir and say I really like this post. It's a great write-up. You clearly thought about the most sensible way to try introducing SRS to your classroom (and hearing about how SRS works in a classroom is great, because that's more informative than hearing about how SRS works for an individual LW poster who's probably more motivated than schoolkids). You tracked which aspects of it worked well and which didn't, and adjusted what you did accordingly. And your write-up acknowledges the aspects that didn't work so well, rather than focusing exclusively on the aspects that did.