AH>           ... using his arms to push himself around?

Actually, he would use sit in an open indian style and use his legs to
skoot. It was a combination of a hop and skoot using legs (sideways on the
ground) and hopping on his butt.  

Similar to your daughter, he went from that to walking and now running.  :)

I had read that the crease tends to be a straight line on kids with DS, but
that isn't always the case.  There are cases of people without DS that have
the same straight line crease, but they are rare.  

AH>           If he has difficulty getting his tongue around the words
AH> because
AH> his tongue doesn't quite fit his mouth, that's not unusual for kids with
AH> DS.

Getting the proper movement in the tounge seems to be the trick with our
son. When I work on words with him, I say them slow and in sections. 
Making a sound and then turning it into a word.  Like
"TTTTTTTTTTTTTRRRRRRRRR  uck".

Once he masters a word, he likes saying it over and over.  He will say
truck and bus all the time when he sees one while we are driving around.

- Mark

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