From Quora: My Answer To "How can I bring up my ACT science score from 27 to 36 within little more than a month?"

https://www.quora.com/How-can-I-bring-up-my-ACT-science-score-from-27-to-36-within-little-more-than-a-month/answer/John-Linneball

I wouldn’t count on getting a 36 (it’s really hard to get a PERFECT score, because the curve is steep at the high end), but you can improve your score by practicing science tests under timed conditions, learning to skim the passages to find the easiest and the hardest, and going to the questions BEFORE reading the passages in depth.

You want to do the easiest passages first, since an easy question is worth as much as a hard one on the ACT (or the SAT, for that matter). Since the ACT science test purposely doesn’t give students enough time to be particularly careful, you should make the hardest section your “sacrificial” section, where you simply bubble in the same answer (say, the second bubble) for all the questions you don’t have time to do.

Almost all the answers to the questions are in the graphs and charts in the science section, so make sure you know how to read the charts and graphs (check the axes, legends, etc., so you know what is being measured, in what units, anything unusual about the data such as limitations, etc). If you can’t find an answer in the graphs and charts, THEN read the passage. One student I helped study for the ACT exclaimed at me “You NEVER read the passage!” I replied, “I know, and you shouldn’t either!”

You’ll also do better if you know the basics of chemistry, physics, biology, etc. - just really simple things like the charge of electrons, protons, and neutrons, dominant and recessive genes, Newtonian mechanics such as F= ma, kinetic energy, specific heat, what causes a plane to fly, etc. If you know these things, you’ll know when a possible answer is wrong - the right answer will match real science. The only exception is when they have “Student 1, 2, and 3” or “Scientist 1, 2, and 3” - a student or scientist who doesn’t understand how the phenomenon being studied works will have the wrong idea, but a question may ask “According to Student 1, would a hammer fall faster than a small marble on the airless surface of the moon?” If Student 1 believes that the acceleration of gravity increases proportionately to the mass of the object being dropped (you know, the ancient Greek theory disproven by Galileo), then the answer is “Yes, because a hammer has more mass than a small marble,” even if you know a hammer and a marble would fall at the same speed, especially when there is no air resistance.

Other than that, keep practicing (say, an hour or two per day) and you should be able to score in the 30s.