in order starting with brown, follow the brown lines first ( to find watermelon just in case), then the red lines (go type in the first elevator code into the elevator), then follow green lines, then the indigo lines afterwards (try to keep up with the indigo lines since they're so long, don't get them mixed up with each other and try to avoid following the indigo lines in the wrong order. Try to get a flash bang too in case Marzia cock-blocks you before reaching the 10th notebook. As for the missing 8th notebook, maybe there could be one in the satanic pentagram room, the Doggos room, red key room (also blue key required to open it), or one in Viktor's room that none of us knew about, or maybe even more likely you overlooked a room (one of the two pink classrooms or the perpendicular-doored green classroom near the bottom of the map; I forgot which of the 3 listed classrooms was it in; has its notebooks on the floor on one side of the room, rather than on a desk, easy to miss. Also i don't know anything about the second level lol. Can you please explain and give me some tips for the second level? I haven't even tried it.
Forgive him, that's the wrong map. He's referring to a previous map edit that I posted that shows a strategy shortcut for the best way to find all 10 language notebooks in a shorter time. Here's the correct map Nikitos meant to show: 
Azure rooms are math notebook-exclusive, lime rooms are language-exclusive, pink rooms have both notebook types, orange rooms are staff only (there is a language notebook in the pizza room and a math notebook hidden in the back corner of the red key room which sould be colored azure and lime as well, pink storage room is also staff-only), cream rooms have no notebooks, tangerine is Phonty's room, purple dots are vending machines, dark green rooms are the first two language notebooks, cyan is the elevator, the red room in the far south with the number 9 holds the final notebook, and the red room in the far north holds a dangerous painting that will kill you upon looking at it.