Why does Mister Rogers change to a sweater and sneakers?
Mister Rogers' Neighborhood takes place in a "television house." Mister Rogers stops by there during his workday to "visit" with his viewers. Since he's coming from his office, he's dressed in more formal business clothes. Changing to more comfortable clothes, like a sweater and sneakers, helps to create a more relaxing atmosphere.
That beginning ritual also gives children a predictable opening with some time to settle in. It provides them with a transition, so they're ready to look and listen when he starts to show something or talk. Also, because zipping a sweater and tying shoes are skills that young children are just learning to do, Mister Rogers sometimes uses that opportunity to talk about those skills and how difficult they can be for young children. He's also deliberately careful about hanging up his clothes and putting his shoes away, letting children see that we are responsible for things that belong to us.
http://pbskids.org/rogers//parentsteachers/series/faq.html