Colby's a dunce...lol She doesn't put her mouth on it, but will put her chin inside the cup and then dump it straight back. She KNOWS how to do it, I've showed her a million times, but she just doesn't pay attention enough. Kayda can do it just fine, but Colby...nope. So..I don't even bother right now. They get sippies at home, when we're out they get a cup with a straw or their sippy cups. People looked at me weird for the first time when I handed Kayda her sippy cup, but I don't care...she's thirsty and it's less mess for her even if she IS three years old.