Knowledge Skills
In general, at 1st level, you could have a 16 stat, maximum, for a +3 and a proficiency bonus of +2, for a total of +5.
For research, you can make attempt after attempt, until I determine you've gone through everything the library has to offer (size matters here, no matter what the sages say) or until you roll a 20, for a DC 25 success.
Large libraries will not only allow more rolls, but may have a bonus of +1 or +2 (or more, if you're in Alexandria).
If you want to see if you know something, with no reference sources, that's a single roll, succeed of fail.
However, for general knowledge off the top of your head (the stuff I tell you you know with out your asking) I'll use passive rolls: 10+ Stat mod and maybe proficiency.
This is generally all Intellect based, of course, but the specific skills may vary for knowledge and general knowledge. Research is Investigation.
In all cases, partial success may be possible.
Oh, and I will make all the rolls so that die roll results don't outweigh the facts given.
This message was last edited by the GM at 19:10, Wed 26 Sept 2018.