Each item on the list is a document or piece of text, many of which turn out to have an unusually large number of exclamation points. Count them and convert to the corresponding letter:
| Item | Number of ! | Letter |
|---|---|---|
| the office sign | 5 | E |
| the first of all the #announcement messages | 2 | B |
| the blurb for Error-Correcting Codes | 21 | U |
| the Welcome page of the camper pre-camp form on the appsys | 12 | L |
| Sarah's first proof that e is irrational | 12 | L |
| the Day 1 schedule | 9 | I |
| the LGBTQ hangout poster | 5 | E |
| Section 1 of Glenn's Crash Course notes | 14 | N |
| the "WET PAINT" sign next to the dining hall entrance | 3 | C |
| the left side of Steve's proclamation that campers won sign-in | 5 | E |
The answer is EBULLIENCE.