check out eBooks....
https://www.chess.com/forum/view/chess-equipment/chess-ebook-apps-viewers
In particular I would suggest considering Back to Basics Tactics by Dan Heisman in ebook format from Forward Chess. It's one of the most instructive and well-written books, introductions to tactics. I think it should work on a Chromebook...
https://forwardchess.com/product/back-to-basics-tactics
You might also find something interesting by browsing Chess Central's download offerings...
https://www.chesscentral.com/downloads/
For web-based training, Chessable is hard to beat.....many of their courses are free...
https://www.chessable.com/courses/
Can someone recommend a good downloadable chess learning software, that'll work on a chrome book.