Cut a piece of paper or cardstock to the size you want and fold the flap book in half. You need to fold your flap book like a greeting card, so double the width of whatever dimension you wish to make it.
Divide the cover of your flap book into equal sections. For example, if your flap book is about the colors of the rainbow, you'll need seven sections. If it's about the planets in the solar system, you'll need eight. You can make as many sections as you can fit; however, the more sections you add, the less space you'll have below for images or writing. Make straight horizontal lines across the flap book cover, and space them out evenly using a ruler and pencil.
Cut into the cover from the edge to the fold across the pencil lines to create the flaps.
Write a category or topic on each of the front flaps. One planet on each flap, for example, if you are making a planet flap book.
Lift each flap in turn and put images or information beneath it about its topic. For example, lift the flap for the planet Mercury and put a small image of the planet on the paper underneath the flap, or write details such as the planet's size, temperature and rotation speed. Continue adding the appropriate information below each flap.
Close all the flaps. Children can carry the small books, collect them in a folder, or glue them on a lap book, display board or in a photo album. To glue a flap book on something, turn it over and apply craft glue to the back. Glue the back of the flap book to the front of the paper or cardboard to which you want to affix it.