This is a small but popular sub-section - fiction that includes science experiments! Reluctant readers, or those who prefer non-fiction, often like these stories. They're basically science with a simple narrative framework. Not great literature, but they get kids reading and interested in science. These are organized from younger to older readers.
I've held this list back for a while, hoping to update it as many of these titles are out of print. Unfortunately, despite the popularity of this odd genre in my library, there don't seem to be many new series of this type.
Doyle and Fossey by Michele Torrey
This series is a lot like the classic Encyclopedia Brown. Each chapter is a self-contained mystery. At the end of the chapter, you try to solve the mystery before flipping to the back for the solution. The twist - they're all science-based mysteries and the clues are scientific facts. There are science experiments in the back, related to the mysteries, as well.
These are graphic novels - each one is centered around a different scientific concept and features a group of kids at summer camp. The counselors pose science challenges and do experiments in addition to the mystery the story written around.
S.W.I.T.C.H. by Ali Sparkes
This series features another eccentric scientist and twin boys. One is crazy about bugs, the other not so much. When they have a run-in with their mad scientist neighbor, they get changed into bugs! A different bug (or reptile) is featured in each book. These are more straightforward narratives, but they include a lot of facts and information about bugs and the other animals they encounter. The boys usually solve each crisis with the WONDERS OF SCIENCE.
Nick and Tesla by Bob Pflugfelder
This series features twins Nick and Tesla. Their stories are a bit more fantastic - their parents have mysteriously vanished and they're living with their eccentric inventor uncle - but the focus is still on the various scientific contraptions they build. Instructions to build your own creations (including robots) and explanations of the science are included.
Club CSI by David Lewman
These books are sort of spin-offs of the popular CSI tv shows. They feature a group of middle school students who use what they've studied in their forensics class, as well as logical deductions a la Sherlock Holmes, to solve various mysteries at school.
George and the Big Bang by Stephen Hawking
This series is for older readers - more middle grade than elementary. It's an adventure/fantasy, fairly typical for the genre, except it includes a lot of scientific information about the origin of the universe, including essays.
Simon Bloom by Michael Reisman
These are similar to George and the Big Bang, but for an older middle grade audience. The hero finds a physic textbook and is able to use the theories of physics like magic - like controlling gravity, etc. Not as much scientific information, but still a sciencey feel.