In recognition of his recent passing, I picked up Donald Sobol's Encyclopedia Brown and the Case of the Disgusting Sneakers. I had forgotten how much I liked these books (I think I read 15 of them in one summer as a kid, IIRC), even though they're really simplistic. But what do you expect from a 5-7 page "mystery" case. I figured out only four of the ten cases properly, and got a couple more close to right. LOL'd at the part where the dad has a bus schedule in his pocket to let the boys go downtown, so his son (not EB) can return a chess pamphlet to another teen who threatened to "kill him" if it wasn't returned to him by 4pm.
The wife and I were talking Donald Sobol/Encylopedia Brown the other day, after hearing about his passing. The one story that stands out in my mind involves melting ice cubes in a glass inside a wall safe.