Books can be made in a lot of different ways and with different materials. Here's a way to make a simple book with a cardboard cover that I've used with kids of all ages over the years.
Step 1: Gather Materials
The first thing we need to do is to gather up our supplies. You need: a right-angle, 18-inch ruler, pencil, x-acto knife, stapler, 5 sheets of white paper, a sheet of corrugated cardboard for your cover, and a cutting board.
The book I'll be showing you how to make here uses 5 sheets of 6 x 18 inch of white paper and a slightly larger sheet of corrugated cardboard, 6.5 x 18.5 inches. You can make your book any size by adjusting the size of the paper and cardboard, but following the same directions.
Tip: I collect sheets of corrugated cardboard from boxes I find at various businesses like grocery stores, furniture stores, and office supply stores. The best cardboard is 2-ply. I cut this cardboard up the size I need it using a mat knife or large paper cutter.
Step 2: Measure the Spine of Your Book
Using your ruler and pencil, make a light mark at the halfway point on one side of the cardboard (9.25 inches) and then mark a half-inch on both sides of the center.
Step 3: Score the Spine
Using the right angle and x-acto knife, score a line along each side of the center of the cardboard using the marks you previously made as guides. Align your right angle with each mark and the long edge of the cardboard and then gently cut through the surface of the cardboard making sure not to cut all the way through.
Step 4: Bend the Cardboard Until the Spine "Pops"
Now, bend the cardboard along the scored lines until it "pops." If the board doesn't easily bend, you may need to score the lines slightly deeper.
Step 5: Tear out the One-inch Section
Now, carefully tear out the one-inch section, leaving the thin paper (or spine) holding the two sections of the cardboard together.
Tip: Tearing this section out is easier if the corrugation in your cardboard runs longways, or perpendicular to the spine, rather than parallel to it.