Allow the children to create a sculpture by gluing all the boxes together, then painting and collaging it. They can take turns working on it in small groups. Later, they can name their sculpture. This activity can go on for days, or as long as the children's interest lasts. The children then went on to build houses, boats, buses, etc.
Children can also build various objects from assorted shapes without using glue.
This is a 24 page book of shape rhymes with pictures that have geometric shapes within them. While reading it to the children, pause long enough on each page for them to find specific shapes.