Bill--you made a good point about the six items on the menu, but I still doubt that it was meant to teach letters and numbers at the same time. (If the number six had also been visible in that cartoon, I'd accept it as a combination tribute.) To the best of my knowledge, Sesame Street has aired only one cartoon in which a specific letter AND a specific number get equal time:
An artist thinks about the letter N, which inspires him to paint a number (the word "Number" appears, highlighted N and all, above the artist's head). He then tries to think of a number whose name begins with N, and chooses to paint a 9. Finally, the artist hangs the 9 next to eight other number-paintings, counting out loud as he passes them. "N for Number Nine!" he exclaims at the end, pointing to his work proudly.