About the Yearbook
Every January, the camp will have a new yearbook so that we can watch how the cabins grow and change over the years. The idea is for this to be an in-character experience, as well. From your character's perspective, this is for the year-round campers. So even though some older campers may be added later, they just weren't pictured because before now they weren't at Camp Half-Blood year round.
Your characters are free to 'sign' (post a message) on yearbook pages until the end of January. At that point the threads will be locked and preserved for the future to look back on, just like a real yearbook!
Missing Cabins are because there are no active campers in that cabin at this time.
Credit for the photos for this year's yearbook go to The Muses Gloss