The Return of the Homework Machine - by Dan Gutman

You might wonder how (or why) an author would mess with such a great book as The Homework Machine, and whether a sequel could possibly be as good as the original.  Surprise: It is!  Like the first book, this story is told through police interviews of each of the major players, which include the four students from the first book and a new cast of characters as well. 

This is the story of four students who happen to live near the Grand Canyon, and who also happen to have invented and used a machine to do their homework for them. After they destroyed the machine (see the first book for that story), it turns out one little part of the machine remained, and that is the focus of this book.  Once it's discovered that this little part, the "brain" of the machine, can be used by its owner to do just about anything, the race is on as good and nasty folks alike try to find it and use it for their own purposes.

This is a good book, but don't read it unless you've read The Homework Machine first.