Portal: Prelude Forum

The picture for the chapter with test chambers 16 and 17 is old, that room (beginning of 17) doesn't look like that.

Also, in 17, there's a room with a box and a tall button (not the big floor one) and an emancipation field followed by a small alcove with a rotating wall. if the wall kills you, dialog about a destroyed box happens and then a second box falls. (and then it reloads fine)