Drop a Master Scientist on the building behind the research table.

Make sure you have a Master Scientist working on it. Just get a Master Scientist and drop him/her on the school. While you're holding onto them, it'll say "They think this can be converted" and while it says that, drop them. They'll convert it. It should be relatively easy. It's one of the first puzzles.

the best thing i found out about the school is , if you don't have puzzle#15 you can use the school drum to distract the GC & other children so they don't get in the way.