RE: Open cup?
We started with the open cup at 6 months just for sips of water, then more regularly around 10 months--we never did a sippy since he's at a Montessori daycare that doesn't allow them. I think it took about 2 weeks of offering it every day to get him to take it, then another 2 weeks for him to stop dribbling down his chin. So about a month to really learn it. Now at 12 1/2 months he's completely off bottles and drinks great from an open cup, he can actually pick it up and put it down on his highchair tray. He has occasionally used the take and toss cups w/o the lid, and I don't think the lip was the problem, but he was picky about cups for a while--it had to look like Mommy's cup, not a kids cup. So now we use a regular clear plastic tumbler or a small heavy juice glass. He does use a straw cup when we go out.
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S.
DS 2003
DS 2009