Q: My second-grade son insists on using a number line or hundred chart to do his math. He relies on it so much I feel like it may be a crutch. I never had much use for these items in school. (I found my fingers and scratch paper to be much more convenient.) I don't want to make him stop using it if that is just his way of learning, but since I never really used them, I don't know if they are just a useful learning tool or a hindrance to his actually learning to do "mental mat