Wally and Beaver escape in the night through their bedroom window, which is a slider (slides up to open).
In subsequent episodes the windows are hinged and open outward.
In subsequent episodes the windows are hinged and open outward.
When Beaver and the classmates put the snake in Miss Canfield's desk, they walk out of an empty classroom. Whitely looks over at the crew on the set and smiles at them before he leaves the room.