ACT Science

The Basics of ACT Science

There are four universal truths about ACT science:

  1. Everyone is horrible at ACT science when he/she first tries it out
  2. Everyone thinks it’s really hard to get good at (and think they need science knowledge to beat it)
  3. It’s the easiest section to beat with proper training and practice
  4. It’s usually going to represent your biggest opportunity for easy points once you figure it all out

The ACT science section is sort of like a really unique iPhone game. The first few times you play it, you have no idea what’s going on, it seems impossible, and you’re tempted to quit. Then you figure out the tricks, get used to it, and it’s extremely easy after that.

In order to dissect the ACT Science section, we need to understand the two essential elements to master the ACT science passage: timing and the overall strategy. However, first let’s understand the basics about the ACT Science section.

ACT Science Section Format

The ACT science section is 35 minutes long, and contains 40 questions. That means that you have about 53 seconds to spend on each question.

The science section’s format is more like the reading section than the math section - which is surprising for some students! Each question on the math section has its own task or problem. But for both the reading section and the science section, there is a passage followed by questions.

There are seven passages on the science section. The passages will contain graphs, charts, experiments, or conflicting viewpoints from scientists. Every passage is followed by four to seven questions.

So, what You’re Tested On ?

Although the ACT Science section includes a wide range of science content, it tests your reading skills more than your knowledge. As the ACT puts it, “the Science Test measures the interpretation, analysis, evaluation, reasoning, and problem-solving skills required in the natural sciences.” In other words, the science section tests skills, not specific facts or topics.

Science test content could include biology, chemistry, physics, space sciences, geology, astronomy, meteorology or anything else that can be classified as Science. However, the ACT does not expect students to be experts or even know anything on such a variety of science topics.

ACT Passage Types

There are three different types of passages you will see on ACT science.

1. Data Representation (30-40% of Questions)

These questions have you read graphs, interpret scatterplots, and explain information presented in tables. The only important skill on this section is your ability to read and understand data and more importantly avoid extra information. As an example, check out this question from an ACT practice test:

Example 1

Example 1

Solution: The topic of this passage is metamorphic rock formation. However, you don’t need to know anything about metamorphic rocks, to break down the chart. The question asks you which conditions a Facies G rock is most likely to form under. Looking at the area of the chart representing Facies G rocks, you can see they form with pressure between roughly 10 and 14 kb, and temperatures between 200 and 1,000 degrees Celsius. Looking at the answer choices, only one (choice J) lists a pressure reading that a Facies G rock could form under. Therefore D is the correct answer.

2. Research Summaries (45-55% of Questions)

These questions require you to interpret the design and results of experiments. Again, specific content knowledge is not at all important. Check out this example question to see what we mean.

Example 2

Study 2
Three study sites were established in order to determine the rate of seed collection by a single species of ant for the plants used in Study 1. In Site 1, Species A plants were absent; in Site 2, Species B plants were absent. Both plants were absent in Site 3. Two seed dishes were placed in each site: 1 containing 20 Species A seeds and 1 containing 20 Species B seeds. The dishes were left out for 48 hours and the number of scenes taken from each dish was recorded.

Which of the following variables was controlled in the design of Study 2?

A. The number of ants in each site
B. The number of seed dishes placed in each site
C. The mass of the elaiosome of each seed
D. The type of seeds taken by the ants in each site

Solution: The topic of this passage is elaiosomes - no one has probably even heard of that word before. A controlled variable is a variable that remains constant. So all you’re looking for is the variable in the experiment that was kept the same. Reading the study description, we see that “Two seed dishes were placed in each site.” This makes B the correct answer.

3. Conflicting Viewpoints (15-20% of Questions)

The final question type on the ACT science section tests your ability to understand, analyze, and compare alternate viewpoints or hypotheses. These questions will center on a single situation or problem, and you will read two different viewpoints and compare the similarities and differences.

Example 3

In 1908, an object from outer space devastated 2000 km2 of forest in Siberia. The object was between 10 m and 100 m in diameter and traveled at a maximum speed of 15 km/sec. It exploded at an altitude of 8 km and released energy equivalent ti 20 million tons of TNT. Two scientists discuss whether this object was a comet or an asteroid.

Scientist 1
The object was a comet, a body made of ices (such as frozen water or methane) and dust. Most of this cometary material is volatile (easily vaporized) and low in density. Friction in Earth’s atmosphere heated the comet to a temperature at which it exploded, high above the ground. The majority of the ices and dust were vaporized in the explosion, which explains why no crater was formed at the site and why no large, identifiable fragments of the object were found. An asteroid would not have been completely destroyed. Intact asteroid fragments that reached the ground would have created on or more craters upon impact and left behind recoverable pieces. Evidence shows that the object decelerated rapidly before it exploded. Because of their low density, commits are capable of such rapid deceleration whereas high density objects such as asteroids, are not.

Scientist 2
The object was a stony asteroid. As it entered Earth’s atmosphere, its high speed created a large air pressure difference between the area just in front of the asteroid and the area just behind the asteroid. The large pressure difference eventually exceeded the structural strength of the asteroid. The asteroid flattened, decelerated rapidly due to the dramatic increase in its surface area, and fragmented before reaching the ground. This fragmentation would have appeared lie an explosion. Calculations show that a comet between 10 m and 100 m in diameter would explode at an altitude much higher than 8 km, but a stony asteroid of that size would fragment at or near an altitude of 8 km. Recovery of large asteroid fragments is difficult due to the area’s boggy soil; however, small glassy fragments were recovered and are believed to be melted and resolidified pieces of the asteroid.

Which of the following phrases best describes the major point of difference between the 2 scientists’ hypothesis?

A. The location of the event
B. The speed the object was traveling
C. The density of Earth’s atmosphere
D. The the type of object that entered Earth’s atmosphere

Solution: The question is asking you to figure out the disagreement between the two scientists. In this case, the disagreement is in the first sentence of each opinion. Scientist 1 says “the object was a comet,” while Scientist 2 says “the object was a stony asteroid.” This makes answer choice D the correct choice.

Science Strategy: Act like a Robot

If you want to ace the ACT science section, you need to act like a robot. You have to do the exact same things, the exact same way, every time. ACT science doesn’t reward creativity, thinking, or acting like a human - it rewards you for acting like a robot that quickly finds relevant information as quickly as possible.

To act like the robot that you need to be, I’m going to provide you with a checklist of steps that you need to use on every single science problem with zero exceptions. The sooner you build the checklist into your routine and use it instead of your own brain when you tackle this section, the better you’ll do.

Here goes the step-by-step checklist:

  1. Go straight to the questions before reading anything beforehand. I can’t tell you how unimaginably important this first step is. On any given ACT science section, you will use maybe 10% of the information printed. Looking it all over beforehand is ridiculous. In about 80% of cases, you don’t even need to know what the heck the study is about. None of it matters. This step alone will save you ludicrous amounts of time without hurting your accuracy.
    One exception: The conflicting viewpoint passage of the section. For this passage, you’ll need to read everything to know what is going on before you look at the questions. More on conflicting viewpoint in the later chapter.
  2. After reading the question, read all the answer choices before doing anything else. Here’s the thing about ACT science - every single question is looking for a very specific answer. The ACT science section is like the exact opposite of the reading section. On reading, you want to avoid answer choices and come up with your answers first. On ACT science, you want to use the answer choices to figure out what you’re looking for.
  3. Read the question again and isolate the exact study, figure, or table that you’ll use to start looking.
  4. Do not PICK the right answers - eliminate three wrong answer choices instead! Trying to “come up with the answer on your own” is a really, really big waste of time. It’s just not worth it.
    Remember: You only have four possible answer choices available to you. Three of them are wrong. Do you think it’s easier to eliminate three stupid, wrong facts, or come up with a scientific hypothesis on your own based on information you barely understand?
  5. Use the most obvious, relevant information available from the “pointed to” portions of the passage to eliminate answers one by one.That’s all there is to do.

It doesn’t matter whether the passage has to do with chemistry, physics, biology, or some combination of the three. You don’t need to read or understand any of it. You just need to get really good at using the above checklist.

Example 4

X - ray spectroscopy is a way of analyzing a mineral composition. When an electron beam is directed onto a mineral, each element in the mineral emits characteristic X-rays having a narrow range of energies. The intensity of all X-rays emitted by the elements is measured. The greater the maximum intensity of the X-rays emitted by an element, the great the relative concentration of the element in the mineral.

Figures 1 and 2 show X-ray spectroscopy results for Mineral 1 and Mineral 2, respectively, under identical conditions. Energy is given in kiloelectron volts (keV); intensity is given in counts per second (sec).

Example 4

Which of the following elements emitted X-rays that had the same maximum intensity in both minerals?
A. Ca
B. Cr
C. Fe
D. Si

Step 1.
Read the question. That is pretty evident
Step 2. Look at the answers. All the answers have to do with two-letter abbreviated element names. Now I know that’s what I need.
Step 3. I’ll want to use “anything having to do with X ray intensity,” which means I’ll need to focus on BOTH FIGURES - this is a comparison problem, so the answer needs to be whichever of these four elements has the same intensity in both figures.
Step 4 & 5. We are only looking at Ca, Cr, Fe, and Si. Nothing else matters because nothing else can be the answer.

Ca is around 400 in Figure 1 and around 75 in Figure 2. Fe looks like about 25 in Figure 1, and about 450 in Figure 2. Si is about 900 in Figure 1, about 650 in Figure 2. Cr is about 100 in Figure 1, and about 100 in Figure 2. That is correct, and B is the right answer.

Again, I cannot emphasize this enough: don’t get detailed until you need to! You don’t have to measure stuff out and be hyper precise about 99/100 times because usually, the other answers are obviously wrong!

Example 5

If an element with an atomic number of 22 had been present in Mineral 1, the energy of the most intense X-rays emitted by this element would most likely have been:
A. less than 3.5 keV.
B. between 2.5 keV and 5.5 keV.
C. between 5.5 keV and 7.5 keV.
D. greater than 7.5 keV.

Step 1 & 2. I’m looking for keV numbers, somewhere in the range of 3.5 to 7.5. Since the atomic number of the new element is 22, it should be placed between Ca and Cr. Therefore, the KeV number of this new element is somewhere between Ca and Cr.
Step 3. We are ONLY LOOKING AT MINERAL ONE! That means that Figure 1 matters. Don’t even look at Figure 2.
Step 4 & 5. Answer A is BELOW Ca, so it’s wrong. B says between 3.5 and 5.5, which happens to be where Ca and Cr are. I mean, this is obviously right, but lets still eliminate the rest. C says 5.5 and 7.5, but that’s not between Ca and Cr. It’s above them both. Same problem with D as with C. So.....B is the answer.