First, look at the map at the back door of the private residence with a doghouse.
One is in the trunk of the police car that is parked on the broken bridge, located on the upper right of the map.
One is in the mailbox of a private residence. You can go to this house by crossing the fallen log bridge in the destroyed area, located in the lower right of the map.
One is in the basketball court over a fence, in the alley, located in the right of the map.

First, get the silver medallion in the Chemistry Lab, and insert it in the foundation of the clock tower in the courtyard, and open the lid of the grand piano.
The riddle which is a hint is on the blackboard of the music room.
The color of the birds correspond to the color of the keys and the height the birds flew correlates to the pitch of the notes.
The birds without voices indicate the keys that do not make a sound.

Obtain a rubber ball from storage on the first floor of the "alternate" school.
Put the rubber ball in a hole at the corner on the roof and let water pour in and flood the gutter.
The drainage outlet is at the upper right of the courtyard map and the key should be found around there.

When you turn the left valve (facing the valves), the left pipe makes a 1/2 turn and the right pipe makes a 1/4 turn.
When you turn the right valve, the right pipe makes a 1/2 turn and the left pipe makes a 1/4 turn.
Once you leave the room, the positions go back to the original.

Since the road between the church area and school area is severed, you have to get there by obtaining "K. Gordon's key" (by battling Split Head at school) and going through K. Gordon's house.
You can go into the Gordon's house from the alley that is running north in the block across from the school.
By the way, check the Teacher's List at the Reception desk so that the location is marked on the map.