Donald Duck in Mathmagic Land

In 1959 Disney released a 30-minute educational featurette called "Donald in Mathmagic Land." Everything about it is superb - the design, the animation, the music, the narration, and the presentation of the material. I remember watching this in school and realizing how interesting math could be.

From Wikipedia:

Donald in Mathmagic Land is a 27-minute Donald Duck educational featurette released on June 26, 1959.It was directed by Hamilton Luske. Contributors included Disney artists John Hench and Art Riley, voice talent Paul Frees, and scientific expert Heinz Haber, who had worked on the Disney space shows. It was released on a bill with Darby O'Gill and the Little People. In 1959, it was nominated for an Academy Award (Best Documentary - Short Subjects). In 1961, two years after its release, it was shown as part of the first program of Walt Disney's Wonderful World of Color with an introduction by Ludwig Von Drake. The film was made available to schools and became one of the most popular educational films ever made by Disney. As Walt Disney explained, "The cartoon is a good medium to stimulate interest. We have recently explained mathematics in a film and in that way excited public interest in this very important subject."