I am also a pediatric PT and love what I do, so I hope my response isn't too intense. If your son was born full-term, that makes him 11 months, correct? In that case, playing on hands and knees should not be too hard. There are a variety of crawling (on the belly) patterns, none of which is really better or worse than the other. Once on hands and knees, usually the legs are pretty symmetrical and move in that alternating pattern (right arm with left leg, left arm with right leg, etc). So, I have a couple questions: 1) Will he take weight on his legs (with you supporting him) with his feet flat on the floor and without completely stiffening or "locking" his knees (in other words he should have the knees bent a little but be able to bounce if he's excited) 2) When he is on hands and knees and lifts his head and/or one arm up, will he keep his knees tucked/bent underneath him? 3)when he sits, is it usually "ring sitting/pretzel style" (this is preferred) or does he "W-sit", which is not the end of the world but is less than desirable 4)Do any of his hip/knee/ankle joints or muscles feel stiff or tight to you or his PT? If you have time to answer those questions, I can possibly give you more insight (and hopefully reassurance!). Feel free to send me a private response and I'll see what I can help you with! =)