Mister Rogers' Neighborhood (1968)

S01E54 Heat and printing

In episode 0054, Mister Rogers makes his entrance with a bag full of bread. Alder showcases the effects of heat on various materials. Meanwhile, X is busy creating posters to promote the upcoming play. King Friday expresses his desire to join in, prompting a title change to "King Friday, Goldilocks, Benjamin Franklin, and the Three Bears."