The frame of a building is formed by connecting horizontal beams to vertical columns. Ordinarily, the columns support the beams, the beams support the weight of the floors, and the floors support whatever weight is on them. Since students know how to make beams and columns from their previous experiments, have them design and make models of imaginary buildings or real buildings such as the school or a famous structure. Cardboard floors should be laid on the beams after cutting out small squares at the corners so columns can go up. Walls can be made of paper with outside features drawn on them and windows cut out.
Floors are usually concrete with a depth of about one foot.
Since one cubic foot of concrete weighs about 150 lbs., have students measure the area of the room, then calculate the weight of the schoolroom floor. Add it to the live load to estimate the total weight acting on the floor. To estimate the live load of your classroom, use a bathroom scale to weigh one average sized student, then weigh him again holding a chair. Deduct the student's weight to find out the weight of the chair, and have students multiply this by the number of chairs in the room. Add up the weights of everyone in the room, estimate the rest of the live load, then total everything up.