W sitting.

My son had a terrible time with "W" Sitting! W sitting is where a child sits with his/her bottom on the floor between their knees, and their legs kind of spread out around them. If you look down on them, it looks like their legs are forming a W. It is a common thing with kids with Autism, but it's also common in neuro-typical children as well. It can lead to a host of issues such as bad posture, poor gross/fine motor, knee issues, hip issues, etc.  I stumbled upon this great blog article that goes in depth into W sitting. (Photo belongs to that blog owner....)

The Inspired Tree House: W sitting

Mosey on over, and take a read!