I love the idea that students are so diverse and keeping teachers on their toes. When we started to discuss the different methods for subtraction, I assumed that it was going to be a short section. I was wrong, the depth that some of the methods goes into seemed to be a little long winded for me. That being said, I can see how that same long winded (to me) could spark that thought in a students mind. Expand using powers of 10. Perform using expanded notation, scratch method, the rules and probabilities; there is so much to what I thought was simple subtraction.
Again, I am going to suggest online game sites for additional help both inside and outside of the classroom. What I have learned in the last few weeks of taking a college math class has been that little in the classroom has stayed the same in regard to math content from the time when I was in elementary school. The changes are for the best and the additional support from both inside and outside of the class should increase the cognition of the student.