Use the Stink Bomb that you can make in the Science Room. (Mix the yellow and blue chemicals and heat them.) Once she is gone, you can open the secret room behind the filing cabinet. You have to have the Blueprint from Nate's Locker.
(see related question)
Mrs. Godfrey will put you into detention if you chew gum in school. To elude her, have a stink bomb ready when she catches you. Using the stink bomb in the detention room will cause her to leave, and you can get to the filing cabinet and secret room. (see related question)
Click on your inventory and select "Use" on the stink bomb. Mrs. Godfrey will run away. Exit the detention room.
in the detention room.
Set off the stink bomb to get Godfrey to leave then go to the right click on the file cabinet in one of the areas. A staircase will open. Go down and get the bell clapper
She is in the Detention Room, and will bring you there if you chew gum in the school. Later, she is there for the Time Capsule uncovering, and when you receive the Island Medallion.
Get detention Set down stink bomb Click file cabinet
In the file cabinet, in detention, in the school.
The entrance to the secret room under the detention room is in the filing cabinet.
You use it when you get put in detention for chewing gum so you can get into the filing cabinet.
you put the stinkbomb on the floor of the detention room and the teacher will leave then you click on the filing cabinet
It is used in detention, so as to be allowed near the file cabinet.
Set off the stink bomb and enter the file cabinet.