Older children can sort into categories based on attributes, such as shape, color, size, and function. Be creative with the categories (e.g., things that are round, things that are red, things that have tails). Allow them to think of a category.
Younger children may need objects or pictures to help name things in a category. Decide on a familiar category (food, colors, clothes, toys, etc.), and cut out pictures from magazines or advertisements for grouping together.