I'd recommend going over the Tips and Notes section of the lesson, it covers the prefixes that correspond with nouns in the Ki/Vi noun class
Wowow, there exist Tips and Notes for each lesson?! Where can I find that in the app? Until now I've always been looking up grammar elsewhere..
unfortunately it is currently only available on the website via your browser, but I will inquire about it. On the website, when you click on the lesson, there will be a key and a bulb symbol. Click on the bulb for the notes. (This is also accessible on the mobile version of the website, and you can go over the notes without having to re-do the lesson)