Please Miss, an Alien Ate My Homework: Sandra Glover, e-[t] mail (London: Andersen Press, 2002)
This is a terribly obvious book, but it just goes to show that just because a book is obvious, doesn't mean it can't be good science fiction. And just because it's good science fiction doesn't mean it can't take on a few social issues at the same time.
When the summer ends, 9 year old Jason hasn't started (never mind completed) his summer project on the Solar system. So he sets down to do what every lazy student does, and plagiarizes a couple of web sites. But suddenly, in new mail (a distraction he finds hard to ignore) a letter arrives from Ojerek, an alien. Jason, not being actually stupid, realises it's an anagram of Joker and dismisses it, until his homework prints out as an alien quasi crocodile with sneakers on.
The book then spirals, with the alien demanding answers so it can do its homework, and Jason coming up with ever more creative with his excuses. He also pulls in his geeky friend Tariq, and eventually (mostly to prove that she isn't the trickster) the smart girl Lucy, so this is also a story about friendship across the sexual and intellectual divide, but it doesn't make heavy weather of it, and Glover makes sure it makes sense within the sf plot to draw Lucy in.
Eventually, it turns out that the alien is a child and his father has just found out. The men in white coats arrive and sequester the computer and Jason's friends suddenly know nothing. To my relief, they turn out not--as Jason thinks--to be mind wiped, but merely to be pretending, thus preserving the sense that even though the incident is over, there will be consequences to this little bit of alien contact.
ps. We didn't learn a thing about the Solar System.