Hey Aaron,
As long as the Chromebooks are up-to-date with a recent version of Chrome there shouldn't be any issues running models with NetLogo Web. Are you linking to simulations on the main NetLogo Web site, or an internal one? Are you able to share those links here? Are students able to browse other pages on the site you are linking to?
Do you see any error messages when running the model doesn't work? If possible, you can try opening the web developer console when opening the model link (Ctrl-Shift-I) to see if any extra errors or warnings are displayed there.
-Jeremy