Other Examples:
- In play, puts several red toy animals together, and then sees several red cats, so puts other cats with them regardless of the color.
By 18 months, forms sets in which objects in each set are identical and objects in the other sets are different, and by 2 years, intuitively forms groups with objects that are similar on some attributes (may be mixed and inconsistent), but not necessarily identical. May use functional relationships as a basis for sorting.