Many Swedish children go to a museum each year to see how their great-great-great-grandparents actually lived. For in that northern country—and in Norway too—people have built museums which are different from America’s big buildings with their many showcases filled with things of long ago. They have built what they call open-air museums. A Swedish man got the idea for such a museum. One day more than sixty years ago that man, a doctor, was far out in the country districts of Sweden. There he saw old, old buildings with furniture like the furniture used long, long ago. He saw people dressed in costumes like those worn by their great-great-great-grandparents. The doctor said to himself, “Why not buy some of those old, old houses, their furnishings, and the costumes of the people, and put them where many people can see them?” Very soon after, the doctor began carrying out his idea. Other people helped him. What a big task it was! They brought together old houses, old churches, old schoolhouses, old windmills, and other farm buildings from all over Sweden. On a large piece of wooded land outside Stockholm they rebuilt homes and constructed whole farms as nearly as possible like homes and farms of the long, long ago. That is the way they made an open-air museum. One day a class of Swedish school children visited an open-air museum. Very soon after they entered the gate they saw a group of buildings. The buildings were made of rude logs which have turned dark brown with age in the sun and rain. The teacher said that the group of houses belonged to one family. The pupils asked, “Why did a family build a group of houses so close together like this?” The teacher told them that in the early days a family in Sweden usually had several houses. They had a house with thick walls and thick roofs where they lived in the winter. They had another house with lighter walls and roofs where they lived in the summer. They had a storehouse in which to keep their food and fuel. They also had a guest house, for in those days the people in Sweden gave their guests a whole house to themselves. [Illustration: A ROOM IN AN OPEN-AIR MUSEUM] The pupils went inside one old, old house which had been built about seven hundred years ago. It is a one-story house with a sod roof. Inside the children found furniture placed about the rooms as it had been placed in those early days. But, of course, there was little furniture. And strangest of all there were no windows in the house. The light the people could get from the sun came into the living room through a hole in the roof above the center of the room. That hole was just above an open fireplace. Through it the smoke from the fire could escape. A long pole hung from the hole into the room below. On that pole was a thin skin which could be pulled into place over the hole when the rains came.