My son went to the same summer camp for 3 summers. He took 3 different classes. His high school granted 3 semester s credits for them but not the grades. His transcript shows “P”. Where/how do you elaborate his actual grades and accomplishments on Common App? Those classes were college level classes for high school students.
There is an extra information section on the writing section. You can enter any information you deem pertinent to his application that doesn’t belong elsewhere, or can’t fit because of size constraints (like the 10-EC max). I’d put it there, explaining everything about it (what it is, where, when, the “p” on the transcript, etc.)