Donald J. Sobol wrote the Encyclopedia Brown books.
Also good in the same vein is "The Mad Scientist's Club" by Bertrand Brinley.
Of course, there are Heinlein's juveniles. In addition to being just plain fun to read, they seamlessly convey an amazing amount of ideas, and a lot of solid hard SF speculation. These are wonderful for adults as well; if you don't like the later Heinlein, you might want to give these a try. I like "The Rolling Stones" and "Citizen of the Galaxy" especially.
"The War Between the Pitiful Teachers and the Splendid Kids" by Stanley Kiesel is a hilarious and damning parody of the public schools, written at about the sixth grade level. I recommend getting it to any child of your acquaintance who is stuck in the public schools.
Going through my collection of kids' books, I was surprised how few science fiction books there were; however, there are a great many stories about talking animals, objects that convey mystical power, magical other lands, etc. I'm pretty sure that reading such tales is part of my attraction to really far out tech; in my lifetime, I may actually see a talking cat made of glass, or a man who can leap tall buildings in a single bound.
Spike Jones wrote:
>
> Chuck Kuecker wrote: Author, please!
>
> The [Danny Dunn] series was conceived by Raymond Abrashkin and
> written by Jay Williams. Abrashkin was almost completely paralyzed
> and would point to letters on a drawing of a keyboard to communicate
> his ideas, quickly developing a shorthand with his co-author, Williams.
> Abrashkin died after the fifth Danny Dunn book.
>
> Jay Williams
>
> born May 31, 1914 in Buffalo, New York
> died July 12, 1978 of a heart attack in London
> married Barbara Girdansky June 3, 1941
> had one son, Christopher, and one daughter, Victoria
> attended University of Pennsylvania 1932-33 and Columbia University
> 1934
> lived in West Redding, Conn.
>
> I havent a clue on Encyclopedia Brown. spike