I'm telling my teacher I self harm?

Posted: 16 Nov 2013 01:20 AM PST

I'm 15 and i scratch myself with my fingernail: it leaves red marks and sometimes bleeds and I thump myself on the same arm with my fist. I only do this when I'm really frustrated. Is this self harm? And what will my teacher do? I've chatted to her before about problems at home but I've never said about self harming. Help