Well, maybe I'll learn something tomorrow.
In MAGIC.MOV, it was revealed that Twilight has an underground laboratory located underneath the Golden Oak. This was where both she and Spike unleashed the R-Dash 5000, and tried to revive Rainbow Dash's somewhat dead corpse (after she was supposedly killed by Fluttershy).
After failing to bring Rainbow back to life, Twilight told Spike to go bury the body at the cemetery (handing him a shovel), and went back upstairs to her bedroom in the library. While she was up there, she decided to write a friendship letter for Princess Celestia (even though she was killed by Discord earlier on). Just as she began writing, she suddenly stopped and tried hard to think about what she learned today (which was nothing). Twilight then gave up thinking, crumpled up the letter, threw it in the trash (along with some other letters), and said that maybe she'll learn something tomorrow.