Hi Kevin,
I know exactly where you're coming from. As a former classroom teacher, I was on my first school's yearbook committee so I was responsible for similar things as you are.
To answer your question: I would recommend that you come up with clever, catchy captions to describe different noteworthy pictures of people, places, and things present throughout the pages and sections of your school's yearbook. Also, depending on how the yearbook itself is organized into sections, you could help the members of the graduating class (high school/12th Grade, I presume?) edit their written submissions for their own personal autobiographies and mementos of what they leave behind at the school in writing and pictorially in the given tribute section of the yearbook. You could also summarize in writing important world events that have occurred and will occur in due time over the course of the current school year. And you could even pay tribute to the teachers at your school in some meaningful written fashion.
Definitely start there. And any ideas that you and other members of your yearbook club come up with along the way will certainly be correlative, I'm sure.
Good luck with it all and feel free to reach out to me (directly) if you have any further questions along these lines! Cheers!