J.T.
My daughter (3 in Jan)uses both a regular glass and a sippy depending on the time an place. She still has spills... I have noticed that with some cups she has more spills. Try lettign you LO practice with a 1oz. measuring glass or a shot glass if you do not have the measuring oz. It is an easy size for them to hold and small enough that my daughter can drink it down without spilling.