Show children a collection of objects that has been sorted. You might use the picture, Face Cutouts, displayed in the sidebar. Ask children to guess the sorting rule. Change the collection and discuss how the rule changed.
Possible student responses
In the first collection the face cards are sorted by color. There are orange faces in one group and blue faces in the other.
The second collection is sorted by hats. The faces in one group do not have hats, and the faces in the other group have hats.