Need help finding directional microphone

I'm enrolled in a history class and government class, and I'm concerned that I won't get all the notes that the teacher lectures us on. So I've been trying to record the classes with the microphone built into my laptop. Long story short, it didn't work out. I was looking for something like a directional microphone that plugs into my laptop so that I can record everything he says and take notes at the same time. Any products you know of would be a big help.
Thanks again.