Off on a tangent - or in my world, procrastination

I know that this blog is supposed to be about writing YA, but about two months ago, I had an idea to write a middle grade novel. I wanted to somehow incorporate my real career, science, into my creative writing hobby. Looking through the Scholastic flyers that my son gets, I didn't see any science series that are really geared toward a slightly older age group. There is of course the Magic Treehouse series, a series about horses, and another one about dinosaurs. There's even one about puppies, but most of these seem like they're geared towards a younger, 1st-2nd grade audience. I want mine to be on a slightly higher level, maybe 3rd-5th grade and I want it to be entertaining as well as informative. I wrote out a first chapter and had my sister, who's a third grade teacher, read it. Her response was good. Then I came up with a plot to set around that first chapter, but the next day dismissed it because it sounded too much like Harry Potter goes to zoology class. I have since rethought it, keeping all magic out of it and focusing instead on real life. What I've come up with is a main character who is intensely interested in science and stuff, but as she makes the transition from grade school into middle school and junior high, she's pressured to drop her interests and conform to the status quo. It's kind of gone a little askew since then and I fear that I may be making it too focused on girly things. It is supposed to be directed more towards girls than boys, but I fear that I may be alienating my boy readers altogether. At any rate, if interested, the first chapter is posted here on the AW website. I direct you there so that you can see what others have said about it. Harsh criticism is appreciated.