What should I do with my haircut?

I have naturally thick, curly hair and I hate it. I would really like to have straight hair, but its a pain in the but to straighten. So this year when I'm going into high school I want to get my hair cut shorter, but the problem is my hair will be too short to straighten(my dad says that my hair is hard enough to straighten with my hair alittle bit bellow my shoulders). What can I do? Any suggestion?