The Last of the Really Great Whangdoodles by Julie Andrews Edwards
This book was totally, outstandingly, awesome! I read it last year in second grade. It's about some children that go to this crickity old house on Halloween. Instead of candy they find a crazy, little scientist. He tells them about Whangdoodle Land and trains them to go there to help the Last Whangdoodle, who is the king of Whangdoodle Land. They wear Srappy Caps to get there! It's great. You'll love it!