Pass around a shape and have children look at it and feel it with eyes open and closed. I use large cutouts--one of cardboard and another of the same shape cut out of sandpaper.
Use pieces of painter tape to make large outlines on the floor of a circle, square, triangle, etc. I ask the child to name the shape before walking around it. Let the children take turns walking or crawling around the edges of the shapes.
For a quiet activity have them hunt for shapes in a magazine and paste them on a paper. Then you can make a bulletin board of shapes with their creations.