In an interview (before the cover was revealed), Goosebumps Series 2000 cover artist Tim Jacobus said he created cover art for the book. Jacobus said the illustration featured a tiny sized kid holding a pencil, warding off a white rat on a desk in a classroom. According to Jacobus, the artwork was finished, but a Scholastic representative called Jacbous and told him not to turn it in. They also said it would be his last Goosebumps cover.
After receiving a request from a fan, Jacobus shared the unused artwork on March 9, 2017.
While this book was never released, the title and cover artwork reveal that the protagonist, a fifth grader, shrinks to miniature sizes.
In the year 2000, R.L. Stine published a one-off book titled The Adventures of Shrinkman. The Adventures of Shrinkman was released very shortly after the cancellation of Goosebumps Series 2000, and the book was the first of six stand-alone novellas that Stine would publish between 2000 and 2001. The introduction to the book says it was partially inspired by the movie The Incredible Shrinking Man, which is the same film that The Incredible Shrinking Fifth Grader derived its title from. The main character of The Adventures of Shrinkman is in the fifth grade, which is the same as the protagonist of The Incredible Shrinking Fifth Grader. In The Adventures of Shrinkman, there is a scene where a white lab rat attacks the miniature protagonist, which is extremely similar to the scenario depicted in the cover illustration for the book The Incredible Shrinking Fifth Grader.
On November 14, 2017, R.L. Stine confirmed on Twitter that the plot for The Adventures of Shrinkman had evolved from The Incredible Shrinking Fifth Grader.
- It is possible that some plot ideas were recycled for the second Goosebumps Hall of Horrors book, Night of the Giant Everything, but nothing has been confirmed.
- The title is a reference to the 1957 film The Incredible Shrinking Man.