I posted a while back really frustrated that Kara did not seem interested or know how to drink from a sippy cup.
Now Kara is 15 months and has finally got the hang of it! Before this all she would drink was milk from a bottle, regardless of whether I put water in the bottle or put milk in a sippy cup. I have about 10 different types of sippy cup in the cupboard which I introduced to her. She finally took to a sippy that you have to bite and suck on - although this still took months of perserverance! It was a case of offering her the juice and her finally picking up the cup and taking it.
Just thought this might give hope to those who are finding a similar problem - they do get there in the end!
