With a class of 30 tying shoes can take up a big part of my day. I don't teach my students how to tie their shoes, because I don't want to interfere with the methods their parents are teaching them at home, but I do recognize my students when they have mastered the skill.
On one of my doors I have an "I can tie my shoes!" board. Whenever a student learns to tie their shoes they get a shoe template printed on card stock that they color and cut out. I add a picture of them and some yarn to complete the project. This door is always a big motivator for the students, and also for the parents who often come in and take a picture of their student's shoe once they have achieved shoe-tyer status : ) These students are also my helpers, and are always more than happy to help tie another students shoes to practice their skills. Since introducing this board a couple of years ago I have spent a lot more time instructing, and a lot less time tying! : )