Hi.. how do u train ur baby to drink from straws?at what age to u train them?

I gave my gal B Box straw cup at 6mths and she could suck. Did not train her. Merely just showed her a mouth action of sucking and she put the straw in her mouth and viola. BBox straw cup is probably easy to suck, it does leak a little. I heard those anti leaking ones are hard to suck. But BBox straw cup is good because it has a weighted ball at the end to follow the water whichever position you hold the cup. I got it online https://www.littlebaby.com.sg/products/b-box-the-essential-sippy-cup