I ummmm did bad on my science test?

Well, i'm really really bad at science. How ummmm do i do better in science. i'm learning metric.. and we did things with triple beam balance, ruler, and graduated cylinder. The graduated cylinder probs, easy, just the water may have evaporated. the triple beam balances, i wasn't here to learn about it cuz i was sick for about 3 days. And the ruler, i just didn't understand the question. everything else. easy, which was conversions. I'm so bad at science. how do i get my grade up? i studied as hard as i could. maybe i'm just no good at school. but i am a straight a student... except for now..