Prior to sorting experiences, give students opportunities to explore and describe objects including geometric shapes in the classroom. These experiences help build the vocabulary needed to help them to sort by color, shape, and size. Ask students to compare objects, noting both similarities and differences. Encourage students to ask questions and to describe their comparisons. This activity strengthens their understanding of classification concepts. In addition, prior to re-sorting objects, students should have experiences sorting objects by a single given attribute (e.g., "Sort the blocks by color.").