My students (9th and 10th graders) have nine verses to memorize every month. The passages were chosen many years ago and have been part of our staff handbook since before I started teaching here; we alternate every other year between Philippians and Colossians, and learn nearly all of each book.
At the beginning of every month I pass out papers with the month’s passage in nice big type. Students can take as many copies as they want—one for their binders, one to keep at home, one to keep in their backpacks, one to post on their locker doors, etc. We read the passage together as part of our normal morning routine. I encourage students to find a memorization method that works for them, and suggest that they try writing/typing it out and/or listening to a recording of the passage in addition to the standard reading-it-lots-of-times method. Other than that I haven’t really involved myself in helping students with Bible memory.
Students are graded according to the number of mistakes they make. The most they can make and still get a passing grade is 12. While a few students have struggled to get a grade better than C or D, I don’t recall any students who have been unable to get passing Bible memory grades (with the exception of those students who clearly put forth little effort).