so that he has a chance to deal with problems by his own initiative. If you solve problems for him, he cannot learn. One day you will not be able to help him even if you want to. Then what?
Self-confidence comes from the belief that he has the ability to solve problems. Only through trial-and-error, he can build that confidence. If you fear that he fails, he will inherit that fear, which will limit his future in a profound way.
Many problems that adults see are not perceived by children. You may be bringing more problems into his life than he should have realized and be bothered by. If he is depressed and anxious, he may be burdened by things he should not be burdened with.
There are not enough caring parents in the world. Your devotion to your children is commendable. But often true love is to let go.
Let your son know that every kid want attention and want to matter, even the trouble-maker, who makes up for his lack of ability to make things good by making them bad. So maybe he can think of some piece of the project for him to do and has the patience to direct and explain, a chance to train in leadership.
If he ever fails, let him fail now in 5th grade, so that he will have more chance to succeed in 10th.
(Avoid hinting to the teacher how she should do her job, or talking about it in front of your son at home. She can tell through his attitude toward her. For your son, the teacher is always great.)