I'm having trouble on ACT science?

I'm taking the ACT next weekend, and i've been taking a bunch of practice tests. I'm getting 30s in reading & english, high 20s in math, but i keep getting 23-25 in science! I dont know what I'm doing wrong; I should be shining in science since it's all reading, and i'm getting 30-34 in reading. I'm reading the pages and underlining whats important, i do not run out of time... I dont know what else I can do! Can anybody help me out? Thank you so much!!