What are you putting in sippy cups (if you are starting to use them)? They want him off bottles by a year old. We found a sippy cup that we like and he doesn't have problems with but now I don't know what exactly I should be putting in it. I was told water to start him on it until he learns. He knows how to suck it now. But still doesn't know that he has to tip his head back to drink out of it. Not sure if we should start putting formula in it or not. Stupid question but not really sure what all we should be putting in his sippy.