The worst thing you can do in the Science section on the ACT is read all of the passages. They are long, confusing, and most of the information is never tested. It’s a waste of valuable time. Instead, if a passage contains charts or graphs (which is usually 6 of the 7 passages), you should only skim and quickly annotate.
Quickly read through the first few lines and get a general idea of the passage’s topic. Maybe it’s about DNA, erosion on a mountainside, or forces on a spring. That’s it. Read no further. All you are doing at this point is orienting yourself to the general topic: biology, earth science, chemistry, physics.
Next look at each chart and graph. Label two things:
1) Axes: Note what’s being measured on each axis. Maybe it’s time, soil sample, resistance, or current. Circle or label what’s being measured. Why? The Science section is basically a scavenger hunt. Each question will give you hints about where to look for the answer. Does the question ask at what temperature cells die in the passage? Go straight to the graph that measured temperature. It’s fast and efficient.
2) Trends: If you get a chart with a bunch of numbers, draw an arrow for each column that traces the increase or decrease of the data. Start your arrow at the smallest value and end it at the highest value like in Figure 3 below. If there’s no trend, note that, too. The ACT always asks about increases and decreases.
Now that you’ve marked where stuff is in the date you are ready to use the time you saved to tackle the questions!