this coment is for sara. i agree that we as older ranks should be helping younger ranks. But what i am getting at is, someone who is going for shodan should be placed with someone of his or her stature, not a 6th or 7th kyu who cant fall. How does this help the 1st kyu. this just makes the 1st kyu softer when he goes for shodan. i like working with younger belts it is a lot of fun, and yes you do learn a lot from them but you also need to have someone who can both uke and nage. Thats all i am saying.
I agree with Janet - I think that the ability, patience and desire to work with students of all levels should not only be encouraged but EXPECTED, especially as one approaches the shodan level. If one is concerned about "going soft" before their test, I don't think they are ready for that rank. There is a lot of practice that goes into preparing for a blackbelt test, and of course it is going to be important to train with senior people to practice advanced and higher intensity techniques. However, finding time for this training is the testers responsibility - it does not mean they get to shirk in their class participation or avoid helping beginners.
As far as the age limit for shodan, I agree with folks who say that it is a matter of maturity and dedication rather than age. Yes, more adults are going to have the appropriate attitude and the dedication to stick with it to shodan level, but if a teenager gets there, more power to them. This is of course the sensei's responsibility to determine - yet another reason we value our teachers so much.