The Dick and Jane Hamlet is also educational - an excerpt:
See Hamlet run. Run, Hamlet, run.
Where are you going, Hamlet?
"I am going to find Uncle Claudius" says Hamlet.
On the way he passes a brook. In the brook he sees Ophelia. Ophelia is drowning.
"Where are you going?" asks Ophelia.
"I am going to find Uncle Claudius."
"Glub, glub," says Ophelia.
Dazed with look-say admiration, I can only exclaim "airplane!" But I was probably meant to say "up" - as this article explains:
The Scott, Foresman series was heavily illustrated with pictures intended to help new readers associate a word with its meaning: a picture of Jane and Sally looking up at Dick's flying airplane above a few lines of text repeating the word up, for example.
That's enough about Dick and Jane. Richard J King has an interesting post about a corrective, the Dr. Seuss books. He identifies two reasons for their success: children loved the hilarious chaos created by the exuberant and irresponsible Cat; and they probably also found them easy to read.
Another important influence, albeit a largely indirect one, was Rudolf Flesch’s Why Johnny Can’t Read, published in 1955. This book argued that children’s primers were not just boring, but educationally flawed, based as they were on word recognition, by which children learn words by memorising them. Flesch, by contrast, proposed a system whereby children are taught to associate letters and groups of letters with particular sounds. This, it was argued, would equip young readers to make sense of unfamiliar words by sounding them out phonetically.
It certainly worked for me.
Update: I found the source for this very silly picture (and here's a translation)