DS is just on 18 months and is very tall with a huge head (height and head are off the top of the charts, weight is 90th centile). He was walking independently at 12 months (walking with a hand held much earlier - 9 months?), but he has never crawled or bum-shuffled and he has no core strength, so he can't get up from sitting down, or sit from lying down. He also can't really climb because of the lack of strength.
He is getting very much left behind at playgroup because all the other kids his age (and considerably younger) are so much more mobile than he is.
I've been trying to work on getting him to climb the stairs at home (as in holding the stair above where the foot is going), and climbing on things at the local playground. But generally the playground stuff is too hard for him, and he refuses to do the stairs a lot of the time. We go for walks on uneven grass in the park. CAn't get him to climb on stuff like chairs; can't get him climbing out of the swimming pool without manhandling him into position, as he can't sit up by himself.
Anyone got any suggestions for what to do? Unfortunately there's no toddler gymnastics or dance within a long way of where we live. I think all is probably normal, he's just hit the jackpot in terms of being the height of a 2.5 year old and having missed out on all the developmental stages that might have given him enough strength to carry his weight around.