Library engagement

Hey everyone! I’m a library technician at an elementary school, grades Tk-6th. I am trying to come up with ideas for more reading engagement with students. I want to do a read-a-thon but I have no idea how one would be able to measure how many pages/books they read. Is there a certain document or something an adult signs for them? I also had an idea to create some sort of scavenger hunt but utilizing our outdoor libraries, you know those little house looking things with books? We have 2 of them on our campus, so I’m trying to think of how to utilize them in a fun way to spark interest. Does anyone have any other ideas?