we never used sippy, just went straight to straws. This is how we got her to use it. A friend who's a PT told me this. We sucked water into a straw and pinched it to trap the water. Then put it in LOs mouth and released the water - to get the water comes from this concept. We had to do this each morning for about a week. After her morning "reminder" she'd drink all day on her own. After a week we no longer had to do the straw trick, she had it down.
My son's been using a straw cup since 6 months - maybe earlier. He didn't need any teaching. DH and I both drink from reusable plastic cups with straws, so my guy saw us doing it and wanted to do it too. We'd let him have sips of ours from 4 months on and at 6 months got him one of the playtex lil grippers. They're natural inclination is to suck, so straws work really well.
Re: sippy cups/straw cups