He is a great teacher, explains things really well. He is really strict on homework, so make you do it, or good luck.
He'll give homework every lesson, sometimes overwhelmingly so, but still good. Because of the types of homework he gives, I aced my exam.
If you don't do the homework...I'm sorry for you
He is a very scary teacher if you don't do your homework and he will email you parents so watch out
Very strict but also a great teacher who is really good at his job
Best English teacher I've ever had. He helped me fight my fear of commas.
A Fantastic teacher. Dedicated, friendly and humourous. Anyone who doesn't like Mr O'Brien doesn't want to learn. Legend of a teacher
Wouldn't remember me for sure but brilliant history teacher from back in the day! Thanks a lot Mr.O, you sparked my love for history!