One of the SLPs I love who specializes in pediatric feeding is Melanie Potock M.S. CCC-SLP from My Munch Bug. I follow her on Instagram which is where I pulled these visuals. She explains so well the pitfalls of sippy cups that I am posting her Instagram pictures for you.
The use of sippy cups can prevent the tongue from contacting with the alveolar ridge (that bumpy area directly behind your front teeth) and promotes tongue thrusting instead (the tongue protrudes past the teeth). This can cause so many problems with language and articulation.
She also has great articles and videos on her web page.
