The Worst Witch series is a funny Harry Potter light for the beginning reader. They tell the tale of Mildred, a student at Miss Cackles Academy for witches faces many blunders in her experiences at school. She's not a very good witch and her spells often go wrong, but do not worry. The book has the terrific feel good ending that young readers love.
These books are on a 3/4th grade level (guided reading level P) and they are thin (the first one is 110 pages) so they're a quick read and good for intermediate readers. There were some UK words that my daughter had trouble with and she reported that it was just a little hard but she says that it was worth it because of the "scary and funny parts." This book would work well as a read aloud for the younger set and is fantastic for the advanced younger reader as well as readers that are ready for beginning chapter books. There was a TV series years ago based on the books (which I was able to get at the library) that is a good reward for when your child finishes the book, there was a movie also which is fantastically bad).
While this is a girl book (taking place in a girls school with female teachers) I think the story is funny enough that boys would like it also.