Can't

I'm really trying, but I want to tear out all of my hair. I don't understand physics, and I don't understand chemistry. I'm trying really hard to pay attention in class so I can ask questions once I get lost, but... I don't understand the first line of the note. I can't raise my hand and say, "You lost me about two months ago. Can you explain?" It doesn't work that way.

I don't think I'll be an astronomer. If I can't do the basic things now, how much hope is there? I really want that job... it's so interesting. But it seems like I'm not capable. I'm trying, but it isn't good enough.

The only reason I'm in the 80s is because of group-work. The majority of my tests have been in the 70s.