Each building will consist of 4 walls and a roof (example photos are of a size 2 building). With the exception of the smallest, the size 1, building, the sides will all be roughly the same size. As seen in the photo above, two plates will have tabs on the sides and two will have slots. On the size 1, you will have two longer sides and two shorter sides making a rectangular building.

For each building, glue a tab wall into the slots wall to make a corner as shown.

Glue the other walls in place just like you did with the first corner.

Glue the roof on slotting into the notches on the tops of the walls as shown.