Atlas and other children his age begin to engage in play activities that are more elaborate and purposeful. what is happening in motor development to support this developmental change in play?

Atlas is probably developing gross motor skills like being able to walk on their tiptoes or to stand on one foot. They are developing fine motor skills like being able to snip things with scissors.

Explanation:

It seems from the question prompt that Atlas is probably about 3 years old and they are acquiring gross motor skills like being able to climb well and to skip. They are also starting to refine their fine motor skills at this age and they can use scissors and hold a crayon and eat themselves. By age 4 they will be able to manipulate clay for example. This is the stage where children are moving beyond just performing parallel play at 2 years old to associative play at 3 to 4 years old.

sounds good to me mate!