Science Fair is also a children's novel by Dave Barry and Ridley Pearson. It is nothing special.
Still reading? Good for you. I assume you are either a Dave Barry fan or have kids, so let's cover those.
This is not the same sort of story as the Peter and the Starcatchers series (also children's novels written by Dave Barry and Ridley Pearson). This is very much a comic adventure, much along the lines of Dave Barry's first solo novel for adults, Big Trouble. It is not, however, of the same quality. Dave Barry is, as always, a master of comedy, and the plot of Science Fair is wonderfully complex and full of gags. Many of the jokes are predictable and hackneyed, which is arguably well and good when your expected audience is only ten years old and hasn't seen these gimmicks before. As a children's book it isn't too bad, although it's not going to be a classic... or even something I'll remember to point out to my kids. Aside from a pleasingly complex plot, it is not particularly notable. Perhaps the biggest flaw in the story is that it doesn't maintain a predictable level of silliness, with the result that certain aspects of the plot seem too unbelievable -- although they would be perfectly acceptable if that level of silliness was maintained consistently throughout the story (I suspect that younger readers may not be bothered by this to the extent that I am).
And speaking of younger readers... This is a pretty good book for kids, as long as you have the right kids. It is fast-paced, with lots of dialog and action, and while it is a little longer and more complex than the average 5th grade read, I suspect that it is exciting and funny enough to make up for that. It comes across as an out-of-control ripoff of Gordon Korman, with a strong overtone of 'This Would Make A Great Movie'. My library has it rated at a 5.5 grade level, but I would add that it is best for kids that have a good attention span and like to read. It would be easy to loose track of what's going on if you got bored and set it down for a few days, and the comparatively high vocabulary level and multiple plot lines could be offputting to some. Overall, a good book for a strong reader who likes silly stories. It fills the same sort of role that Gary Paulsen's Dunc and Amos did when I was a kid, although I must admit, the Dunc and Amos books were probably a step down in literary quality.
A very quick plot summery: The government of the Republic of Krpshtskan (a joke country akin to Elbonia) has decided to take down America. Their plan involves a secret agent who is living in Washington DC -- and working in Hubble Middle School. As it happens, Hubble is the perfect place to assemble a super-weapon, because 1. it has a rich benefactor that sponsors elaborate science fairs, 2. the wealthy (and competitive) families of some of the kids will spare no expense to win, and 3. for the past few years, these wealthy kids have come to rely on a mysterious source within the school to provide them with plans for winning projects. Yes, this source is the secret agent, and yes, this year the plans will be extra special. Enter Toby Harbinger, who is not one of the wealthy, popular kids, but has noticed that they seem to be getting some unfair help. He investigates further, but finds that no one will believe him... and wacky adventures ensue. There are other subplots involving Star Wars memorabilia, Creepy Science Guy, FBI agents, and inept Krpshtskanian government officials.
The book ends with a strong suggestion that there could be a sequel, although Ridley Pearson's site currently lists Science Fair as a 'stand alone book'.