The most effective way to show concern for a person is to make him feel that he has a sense of being, to make him appreciate his own value. This is especially true for retired teachers, who may have had a great career when they were young, waving their hands on the three-foot podium, but now that they are retired and fading out of the limelight, this sense of disparity will make them depressed, and they will feel that they don't have any value anymore.
So the care of the retired old teacher is the most important thing is to care for the soul, which is better than the care of his life, you can often go to visit the teacher, often talk to him about the academic aspects of the problem, ask him questions, listen carefully to the teacher's answer, this time must be the teacher's happiest time, because any teacher he is most proud of is that he taught a good student. The most successful is to pass on their lifelong learning to their students without reservation.
In addition to asking some questions, you can also discuss the situation in the world today with the old teacher, talk about family and national issues, so that the teacher feels that he is not out of touch with the society, as if back in the year on the three-foot podium in general.
Of course, you can also express some material concern for the teacher, but do not be so direct, to be euphemistic, because it may hurt the old teacher's heart, may make them feel that they have no dignity, a lot of years old, once your teacher but now you need to take over, he will be a little sad.
You can say to the teacher, I now come to you to ask questions, is an extra tuition, you have to charge me tuition, of course, not necessarily need to give money, you can look at the family need what supplies to buy some at home, so that on the one hand, you express the concern of the teacher, on the other hand, both sides will not feel embarrassed. The first thing you need to do is to get your hands on a new one, and you'll be able to do it.