This is probably one of the easiest crafts you'll ever make! We made a bunch of these bookmarks with a group of 11 year old girls who are getting ready to go back to school. I forgot my camera, so I wasn't able to take a picture of all the cute and creative bookmarks they made. Here are some that I made to give to my kids teachers when they go back to school here in a few weeks.
When choosing ribbon, make sure it's not too wide. Thinner ribbon works best so you can tie several different ribbons on.
Also, make sure to tie the ribbon on the correct end of the clip so it will clip onto your book page like in the picture below.