rubber room

rubber room
 n.— «The use of a controversial isolation room in a Dundas, Ont., elementary school has left parents with mixed feelings.…The room, which has been referred to as “the rubber room,” and “the box,” was constructed in January at Central Park School in Dundas at a cost of about $1,800 and put into use without consultation with parents or trustees.» —“School board plans alterations Reaction mixed on isolation room” Globe and Mail (Toronto, Canada) June 20, 1984. (source: Double-Tongued Dictionary)