My kid knows how to drink from a regular cup but is unable to use a cup with a straw. How do I teach my kid to use a cup with a straw in it?
It's better to start with a squeezable closed bottle or a packaged juice with a small opening for the straw. You can keep the straw in their mouth and squeeze the packet or tilt it such that the juice will flow into their mouth even if they don't suck. While doing this, make a sucking motion with your mouth (if your toddler is too small to understand verbal instruction) and then stop squeezing so that it will stop the flow. If the child likes the juice, they will try and imitate what you are doing and will soon get a hang of it. Once they are able to do it, you can slowly transition them to a cup with a straw.