ET A-school getting tough

My son is close to halfway through ET A-school and has consistently scored in the 90's, hitting the books hard. He has just encountered a new unit that exceptionally challenging, and scored below 75 for the first time. He did open study and asked friends for help but is still lost and thinks he will fail the next test also, and have to go talk to the chiefs, which he is very worried about. He has still ranked in the top half of the class. Is there anyone he can talk to or some way to get additional help before that happens? He is feeling defeated and wishing he wouldn't have picked the ET rate, for the first time. Was loving it up until now. Any help appreciated.