The Wonderful Flight to the Mushroom Planet #1 by Eleanor Cameron*

When David's father reads aloud a peculiar advertisement in the newspaper, he knows that he and his best friend Chuck must answer it.  Mr. Tyco Bass asks in the ad for a boy or two boys to build a space ship about eight feet long with materials available to them.  David's father scoffs at the ad but David immediately draws up plans for the ship.
Soon David and Chuck find themselves interacting with Mr. Bass and learning about a new planet that the scientists cannot view with their instruments.  To their astonishment, Mr. Bass asks them to travel to the planet (which he believes is his ancestors' home planet) to help save it.
Ms. Cameron writes at a pace that keeps the reader engaged and shares a fun adventurous story.
I do not care for science fiction but I thoroughly enjoyed this story! I have recommended this book to my third grader.
*Highly recommend.
*Borrowed from the library.
Reading Level: 4.9