The rural areas were (and still are) thinly populated, so in days before easy travel, the teachers came to the settlements and conducted school for some months. In some cases they stayed at the farms, in other cases the schoolhouse had accomodation. The teacher then ate at the farms.

The roof is made of wood, thatched with birch bark (which is air- and waterproof) and then the turf on top as insulation. The grass spends shade for the roof on hot summer days, narrowing the dayly temperature variation in the structure and so minimises the wood's labouring due to temperature and humidity changes.
Construction detail http://public.fotki.com/stein_s/travels/norway_-_norge/2006-08_the_folk/img_3199_norsk_folk.html