When the child was in the third grade, the parents of his classmates invited our child to attend his child's birthday party. How to decline?

Why did you refuse? Let children participate in these activities more, which is conducive to the growth of children's communication skills. Since we are classmates, we really should participate more. If you really think it is unnecessary for children and parents in this family to communicate, buy small gifts. For example, Ben, books (that is, stationery) should be sent to that classmate in advance, and then parents should be told to go to relatives' homes on this day, but I suggest that children participate.