Foster's Journal

History
Foster's Journal first appeared in This is Your School Part 2. Right in the beginning of the episode, we see a shot of Foster and Victoria where the journal is visible, sitting closed on Foster's desk. The first mention of the book by a character is when Adam Hendrickson brings up his encounter with Foster, and Victoria asks him "was he holding a black journal?" Victoria revealed to know little about it's contents, only having seen quick glances, "weird graphs, and like, geometrical sketches". The Journal itself was the highlight of the I Have The Answers sequence within the same episode, where Foster hints towards the secrets that might lie within.

Future
It is assumed that The Journal will be an ongoing mystery throughout The Adam Hendrickson Show. In the only existing after-credits scene, which was included in Foster and The Journal, the journal is seen spinning in space, alluding to it's mysterious quality.