Quoting Stephiiii:" how'd you get her on a straw sippy? DS doesn't seem to grasp the concept, is it just something that will come to him? he just turned 9 months."
Just keep offering it. I started a regular sippy at 3 months and at 4 or 5 months I started the straw cup, she took to it right away actually. Every meal and when playing just offer it with 1/2 c of water so 125ml or 40z whatever way you want to look at it. lol It will come when ready. try switching the type of straw cup maybe a thicker one or a smaller one.