Murder in the library
"Murder in the library" can be a project involving many people in the school: we found a dead body in the library. Nobody knows the dead person, nor the killer. We will have people helping:
The nurse of the school can tell us what time the person died
The security guards can tell us if anyone came to the school the previous day
The art teacher can teach students how to make a portrait of the suspect, according to the description from the cleaning staff
The science teacher can show us how to use the microscope, how to identify different kinds of blood, etc.
We can find books in the library (fiction and non-fiction) to help us with the investigation