I used to read them all the time... but this was when I was in 2nd, 3rd, 4th grade, sometime around then. I started off with reading the Hardy Boys books in my elementary school's library... but those were from the 60s. I then read some newer, more updated Hardy Boys (they actually had a tape player in the van now!) and the Hardy Boys casefiles. I thumbed through one of those books a few months ago and couldn't believe how big the print was... probably 11-point or so which is humungous for a book like that.