OP is probably referring to the types of books generally supplied to small children who are first learning how to read. They tend to be extremely short (no more

OP is probably referring to the types of books generally supplied to small children who are first learning how to read. They tend to be extremely short (no more than a few dozen words in the whole book); heavily illustrated; and use simple words and sentence structure. By extension, I gather they’re looking for examples of well-engineered programs small and simple enough for a true beginner to thoroughly grok within a short period. Presumably something in a few hundred lines of code that avoids unnecessary indirection or cleverness.