Nibbles and Gorillas was the first piece of code that I saw and was amazed how it worked. It taught me why we need to use functions and subs. And as a 13 year old it was fascinating to understand those concepts.
And most of the programming I learnt was from the snippets of code in the QBasic help files.
At my highschool - the progression was Basic on Apple IIe machines and then Pascal. I remember talking to an older friend who was already doing Pascal and he said, "There are no line numbers." I was stunned. "What?! How can you write a program without line numbers?"
Yup, the first lump of non-line-numbered BASIC I'd ever seen. I learned on the Spectrum 48K and when I switched to PCs I kept all of the limitations with me until I read those two.
And most of the programming I learnt was from the snippets of code in the QBasic help files.