It's a little known, but true, bit of trivia that the character who appeared on the most DC covers in the 1940s was not Batman or Superman, but Robin, the Boy Wonder Batman and Superman appeared on virtually the same number of covers because they both popped up on their eponymous mags, their original mags (Detective and Action) and on every cover of World's Finest. But Robin was on every cover of Detective, Batman and World's Finest, plus a slew of Star Spangled covers.
In the first two stories, the pattern was the same; Alfred observed some object in the Batcave's trophy room and upon inquiring about it, learned that it was a memento of one of Robin's solo cases: Both those stories featured other youngsters in trouble, a common theme in the Robin adventures for obvious reasons. In the first one, Robin goes undercover into a reform school and learns that a building engineer (apparently a janitor) is tutoring the kids in the ways of adult crime. In the second, he helps out a boy movie star who's secretly a chicken despite apparent bravery in his films.
The third story is a very offbeat tale of three boy wonders: Robin, a child violinist, and a brilliant teen-aged scientist. They are given a test to escape a house that will blow up in 30 minutes, but getting out alive is not easy: But it turns out it was all to settle an argument on what type of child prodigies to train at a new school for geniuses: Robin also developed his own "Rogues' Gallery" during this run. Perhaps the most notable was The Clock: The Clock made at least three appearances in the Robin solo stories, and a different version was later retconned as Batman's first foe (in Detective #265).