The bookmarks are created by your students. Anytime you assign a new novel reading you can have them decide on the vocabulary. They use the new novel to identify unfamiliar words. They write the word, the page number, and a brief definition.
This is a great assignment to give after a quiz or test. It keeps kids learning yet quiet so others can continue to work on their quiz/test.
This would also work with a pre-made vocabulary list. Students find the word in the book and define it using context clues.
You need to provide the form for the bookmark.