You know, elderly people just need your company. When you are with them, just sing, play or crack jokes and bring them food or have it with them. Talk something which is of interest to them. They are not interested in listening to wisdom from you, or learning any new techniques from you. Don't behave like a teacher with your elderly parents. Casually, you may give a few words of wisdom. Observe if they are absorbing it. Otherwise, just being with them is good enough