Simplify the following text for a Grade 7 native English-speaking person.
Original: Louvers originated in the Middle Ages as lantern-like constructions in wood that were fitted on top of roof holes in large kitchens to allow ventilation while keeping out rain and snow .
Simplified: Louvers come from the Middle Ages as lantern-like constructions in wood that were fitted on top of roof holes . They were put in large kitchens to allow ventilation while keeping out rain and snow .