Dan Gutman 
My Weirdest School #8: Mrs. Master Is a Disaster! 

With more than 30 million books sold, the My Weird School series really gets kids reading!In this eighth book in the new My Weirdest School series, its Grandparents Day at Ella Mentry School! Alexias grandmother Mrs. Master makes weird inventions for a living, but A.J. and the gang come up with the weirdest invention of all. And theyre going to make a bazillion dollars from it! Will they succeed? Or will their great big idea be flushed down the drain?Perfect for reluctant readers and word lovers alike, Dan Gutmans hugely popular My Weird School chapter book series has something for everyone. Dont miss the hilarious adventures of A.J. and the gang!