Books and movies often seem to go hand-in-hand, don't they? Who hasn't read a great book and then been overjoyed to see it made into a fantastic movie. Movies can bring the stories in books to life in ways that rival the imagination.

If you're a fan of movies, you might enjoy 3D movies. There's nothing quite like seeing the action on the silver screen jump right out at you. But did you realize that there have long been books that could do something similar?

If you think back to your childhood, you'll probably remember what we're talking about. That's right. Do you have any favorite pop-up books that you loved because the action literally jumped right out at you as you turned the pages?

Pop-up books are just one particular type of a larger group of books known as movable or mechanical books. In addition to pop-up books, movable books include transformations, tunnel books, flaps, pull-tabs, pop-outs, pull-downs, and even some types of three-dimensional greeting cards.

Pop-up books come from the art of paper engineering. They are associated with origami, because both involve paper folding. Unlike origami, however, pop-up books rely on scissors and glue, as well as heavy card stock as opposed to paper that's easily folded.

No one is sure exactly when the first movable book was created. However, historians have uncovered a manuscript for an astrological book from 1306. The author, a Catalan mystic and poet named Ramon Llull, used a revolving disc called a volvelle to help illustrate his astronomical theories.

Although pop-up books have long been popular with children, the first movable books were designed for adults. Rather than entertainment, early movable books attempted to overcome the inherent limitation of two-dimensional books to help early readers understand developing scientific theories. The first movable books meant to entertain children weren't developed until the 18th century.

The first movable books for children were made by hand by skilled craftsmen. Over time, these time-intensive processes were automated with the help of machines.

Children's pop-up books became very popular all over the world. Publishers even began to reprint traditional fairy tales to add new pop-up features to delight children and spur them to read more. Today, hundreds of new pop-up books are produced each year.

Making a pop-up book requires a lot of skill and planning. First, all the usual work that goes into a normal book is required. Then, once the storyline and illustrations are complete, the project goes to a paper engineer who must determine how many of what kind of movable elements should go into the book.

Paper engineers must be both imaginative and practical, as they seek to entertain while also designing a book that will last for years and years with repeated readings. Great care must be given to designing pop-up elements that will not break over time.

Paper engineers must ask themselves which pieces need to be attached and in what way. How long should pull tabs be? How much glue should be used? Mathematics play an important role in this phase of making pop-up books.

Some pop-up books make an impact with more than just paper. For example, small sound chips are sometimes used to play recorded messages or music, making books that please both the eyes and the ears!

Although modern printing presses can generate all the necessary pieces of pop-up books quickly and efficiently, many pop-up books are still assembled by hand. Sometimes it takes groups as large as 60 people to put together a single book in an assembly line that involves folding, cutting, inserting, connecting, and gluing!

Wonder What's Next?

A cold front is moving into Wonderopolis overnight. Better watch out for ice tomorrow!