I came across an interesting thought I would like to share:
Instead of focusing on the breastbone/elbows/knees, they should be building up girls’ egos,
Rabbi Yisroel Reisman NEVER talks about tznius, because he knows the damage its misrepresentation has caused. If a child has learned their other subjects properly, if they have been valued and ordered to value herself, then she will dress accordingly. (Comment by Princess Lea on June 6, 2013 at 10:36 AM)
Will kids learn modesty alone? I don’t know. It probably depends a lot on the environment, group pressure, role models, etc. There is probably no guarantee that a child will learn the values you want it to learn. But again, there are never absolute guarantees. On the other hand, if the decision to dress modestly is not forced from the outside, but comes from within, it will not feel like a burden, but be a positive force. And as such it has a higher chance to hold even when the child grows up and enters a different environment (like university, work, where the chance of very immodest general culture is high).