Updated December 10, 2025

9 of the Hardest ACT Science Questions (With Solutions)

Bonus Material: ACT Score Ranges for 750+ Schools

What are the hardest questions on ACT Science? And how can you prepare for them – especially if science isn’t your favorite subject?

The good news is that ACT Science requires very little science knowledge. It’s mostly about finding and using information. And that means that test-taking strategies are extremely useful.

Based on 20+ years of experience preparing students for the ACT, we’ve identified some of the toughest kinds of ACT Science questions, along with what makes them so hard – and how to solve them.

In this post, we break down 9 of the hardest ACT Science questions and show you exactly how to solve them using efficient strategies.

Curious what ACT Science score you should be aiming for in the first place? We lined up the average scores at hundreds of schools so you can see what it takes to be a competitive applicant. Find the schools on your list in the free download below!

Jump to section:
What are the Hardest Topics on ACT Science?
Interpreting Data
• #1: Multi-part questions
• #2: Using outside knowledge
Scientific Investigation
• #3: Multi-step questions
• #4: Extrapolating data
• #5: Science Jargon
Data Representation
• #6: Juggling Multiple Variables
• #7: Multi-Step Math
Research Summaries
• #8: Predicting Results
Conflicting Viewpoint
• #9: Summarizing Arguments
Key Strategies for ACT Science
Next Steps

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What are the Hardest Topics on ACT Science?

What are the hardest ACT Science questions? That depends on your personal challenges and strengths. But there are a few question types that tend to be on the harder side for many students.

• Combining information from multiple sources (questions 1, 2, and 7 below)
• Drawing on outside knowledge (question 2 below)
• Wading through scientific jargon (questions 5 and 8 below)
• Going through multiple (often simple) steps to reach the answer (questions 1, 5, 6, and 7 below)

And as for all the question types you’ll see on the test, here’s what you can expect:

Topic	What it means	Percentage of questions	Number of questions
Interpretation of Data	Read and understand graphs and tables	40-50%	16-20
Scientific Investigation	Understand how experiments are set up and reason how similar experiments would unfold	20-30%	8-12
Data Representation	Recognize relationships in data using graphs and tables	6.3-12.3%	3-5
Research Summaries	Interpret experimental results and evaluate experimental setups	11.3-21%	5-8
Conflicting Viewpoints	Compare and analyze different explanations for a scientific phenomenon	3.8-7%	2-3

Below are 5 passages, one on each of these topics, with 2-3 questions each.

One important strategy tip: For each passage, before you start wading through the data, read the questions first. ACT Science gives you only 40 minutes to answer 40 questions – that’s just a minute per question. If you try to read every detail of the data, you might get into a time crunch.

So, instead, start with the questions and use them to guide and target your reading of the data.

Now, on to the questions. 

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Interpreting Data

The hardest types of data interpretation questions might:

• Ask you to synthesize information from multiple charts or graphs at once
• Require specific information that’s “buried” in the text
• Complicate simple questions by piling multiple steps on top of each other 

The next 2 questions are about the information below.

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#1: Multi-part questions

This question is about the “Interpreting Data” information set above.

Which of the following observations for long-beaked echidnas was (were) the same in both Habitats B and C?

1. Average nest size
2. The number of times Behavior 4 was displayed
3. Average display time for Behavior 5

1. F. 1 only
2. G. 3 only
3. H. 1 and 2 only
4. J. 2 and 3 only

Why this is a hard question → It contains multiple steps that require you to look in several different places.

After you read the question (before reading the data), the first thing to ask yourself is where to look for the answer.

Here, you’re told that you’re interested in

• Long-beaked echidnas
• Habitats B and C

That means you can completely ignore anything about short-beaked echidnas or Habitat A. Don’t even waste your time looking at irrelevant data!

Even better, you don’t have to find the information first to answer the question. Instead, start with the answer choices and use the process of elimination.

Start with answer F, which claims that only nesting height was the same in Habitats B and C for the long-beaked echidna. To evaluate that, zoom in on the figure that shows nesting height: Figure 1. 

Glancing at the average nest size of the long-beaked echidna in Habitats B and C shows you straight away that it is not the same, so you can cross off answer F. You can also cross off answer H, since statement 1 clearly isn’t true.

On to answer choice G. This is asking about the average display time for Behavior 5 (again, for long-beaked echidnas in Habitats B and C).

First step: where will you find this information? In Table 3. Ignoring the parts about short-beaked echidnas, you can see that the numbers for long-beaked echidnas are the same, so answer G is possible.

Finally, evaluate answer J. We already know that observation 3 (about behavior duration) is the same, so we only need to check observation 2 (about behavior frequency). First step: where are you going to find the information about the number of times a behavior was displayed? Table 2.

We’re only interested in the number of times Behavior 4 was displayed in Habitats B and C, so focus on those areas of the table:

Behavior	Number of times behavior was displayed in Habitat:
	A	B	C
1	10	12	N.A.
2	6	15	N.A.
3	48	26	N.A.
4	N.A.	10	34

These numbers clearly aren’t the same, so answer J is incorrect. That leaves us with only statement 3, which is answer G.

Answer: G.

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#2: Using outside knowledge

This question is about the “Interpreting Data” information set above.

A student claimed that echidnas are ectotherms. Which of the following explains why this claim is incorrect? Echidnas are:
A. mammals and primarily generate heat from internal metabolic processes to maintain body temperature.
B. mammals and primarily absorb heat from the surrounding environment to maintain body temperature.
C. reptiles and primarily generate heat from internal metabolic processes to maintain body temperature.
D. reptiles and primarily absorb heat from the surrounding environment to maintain body temperature.

Why this is a hard question → It requires a little bit of outside knowledge, and it requires you to find information that’s buried in the question intro.

Glancing at the answer choices, you’ll see that there are two things you need to decide on:

• Are echidnas mammals or reptiles?
• Do they primarily maintain their body temperature by generating heat or by absorbing heat?

Notice that, despite the jargon in the question, you do not need to answer whether echidnas are ectotherms. That’s already answered for you (they are not).

If you happen to know that echidnas are unusual egg-laying mammals, great! You’re halfway there. But if you find yourself facing a question that seems to require over-specific outside knowledge like this, skim the text – and especially the introduction – for clues.

In this case, the answer is hiding in plain sight:

Passage 1

Short-beaked and long-beaked echidnas (2 species of mammals) behave differently when the species are together in a habitat than when the species are in separate habitats. 

It’s right there! Now you can cross off choices C and D.

Now: do echidnas, as mammals, generate or absorb heat?

There are two pieces of knowledge you might have up your sleeve:

• Mammals primarily generate heat instead of absorbing it. Echidnas are mammals, so they primarily generate heat.
• “Ectotherm” means that an animal primarily absorbs heat instead of generating it. You’re told that echidnas are not ectotherms, so they primarily generate heat.

You do not need to know both of these things – either one is enough to tell you that the correct answer is A.

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Scientific Investigation

The hardest types of questions on scientific experiments might: 

• Require you to know some basic terms related to experiments
• Ask you to skim and summarize a lot of information about the experiment
• Predict results that aren’t given to you in the question

The next 3 questions are about the information set below.

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#3: Multi-step questions

This question is about the “Scientific Investigation” information set above.

Based on the results of the study, approximately what percent of the seedlings that were grown in soil with a pH of 5.0 survived to 10 weeks?
F. 12%
G. 20%
H. 88%
J. Cannot be determined from the given information

Why this is a hard question → It has multiple steps that build on each other, and it contains a classic trap: asking for the opposite information to what you’re given.

To start, break this down into the relevant steps:

1. Which seedlings were grown in soil with pH = 5.0?
2. Of those, how many survived to 10 weeks?

Start with step 1: you can see that pH information is in Table 1. And the group of seedlings with a soil pH of 5.0 is Group 1.

Now, step 2: how many seedlings from Group 1 survived to 10 weeks?

Seedling mortality info is in Table 2. We’re interested in Group 1, so the relevant information is the 12% figure:

Table 2
Group	Average dry mass (g)	Seedling mortality (%)
1	0.20	12
2	0.65	4
3	0.95	2
4	0.60	8

Where do we see if the seedlings survived to 10 weeks? We don’t. Here’s where the classic “opposite” trap comes in. 

Table 2 shows how many seedlings did not survive, and we want to know how many seedlings did survive. (Specifically, to age 10 weeks. Skimming the description of Table 2 above tells you that we don’t have to worry about that: the mortality percentage is given for 10 weeks.)

If 12% of the seedlings died, then 100-12 = 88% of the seedlings survived. That gives us answer choice H.

Answer: H.

If this feels complicated and you want more guided practice, think about reaching out to our team. Many of our tutors are perfect ACT scorers themselves, and they can help you with both test-taking strategy and time management.

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#4: Extrapolating Data

This question is about the “Scientific Investigation” information set above.

Suppose that as the plant dry mass increases, the root-to-shoot ratio (a measure of root mass relative to shoot mass) decreases. Based on the results of the study, the plants in which group most likely had the lowest root-to-shoot ratio?
A. Group 1
B. Group 2
C. Group 3
D. Group 4

Why this is a hard question → It requires you to make predictions of data you don’t have.

Your strategy for questions like this is to translate the question into something that relies on the data you do have already.

Close-read the question: what do you want to know, and what do you know? 

• Which group had the lowest root-to-shoot ratio?
• Bigger plant dry mass → lower root-to-shoot ratio
• So: which group had the biggest plant dry mass?

Now, you’ve turned this complicated question into a basic question about reading Table 2. The biggest average dry plant mass belongs to Group 3, so that’s your answer.

Answer: C. 

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#5: Science Jargon

This question is about the “Scientific Investigation” information set above.

The effect of what abiotic factor was examined in the study?
F. Average dry mass
G. Soil pH
H. Seedling mortality
J. Average precipitation

Why this is a hard question → It doesn’t have to be, but it throws in a scientific term (“abiotic factor”), which could be intimidating if you forget what that means.

The good news is that it doesn’t matter whether you remember this term. The question is just asking which factor’s effect was examined. 

In other words, what factor were the scientists varying?

You don’t need to go through the tables to figure this out. The answer is hiding in plain sight at the beginning of the intro:

“Scientists conducted a study to examine how soil pH affects seedling growth and survival.”

This isn’t really a science question at all – it’s just asking you to find the necessary information in a big pile of text and data. And to do that, the introduction is often a good place to check.

Answer: G.

Wondering how to set your goal score on ACT Science? Here’s the most recent data on how admitted students at over 750 schools scored, so you can see what you need at your goal schools.

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Data Representation

The hardest types of data interpretation questions might: 

• Present data in unusual ways (other than your standard x,y-axis or table)
• Require multiple steps that draw on information from different data representations
• Throw you off by using unfamiliar units

The next 2 questions are about the information set below.

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#6: Juggling Multiple Variables

This question is about the “Data Representation” information set above.

Based on Figure 1, which of the following values of initial temperature and cooling pressure P would produce the smallest average grain size in a sample of Rock R?

A. 900°C and P = 5.5 × 10³ Pa
B. 900°C and P = 5.8 × 10³ Pa
C. 1200°C and P = 5.5 × 10³ Pa
D. 1200°C and P = 40 × 10³ Pa

Why this is a hard question → It asks you to get multiple pieces of information from the same figure. A lot of students find that confusing.

First things first: what do you know already, and what do you want to know?

• We have a graph showing how temperature and pressure affect grain size.
• We want to find the temperature and pressure that cause the smallest grain size.

You don’t need to know anything about rocks to answer this question. And notice that you don’t even need any information from the passage. You just need to be able to read the figure.

In Figure 1, find the spot that shows the smallest grain size. Grain size is on the y axis, so that spot is here:

Now, just read the graph. The spot with the smallest grain size:

• Is on the solid graph line, so it’s at 900°C.
• Occurs at a pressure of 5.5 × 10³ Pa

That gives you answer A.

Answer: A.

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#7: Multi-Step Math

This question is about the “Data Representation” information set above.

A geologist analyzes 50 g samples of four different rocks. The mass of quartz in each sample is shown in the table below. One sample is Rock R.

Sample	Mass of Quartz (g)
A	45.0
B	36.0
C	18.0
D	22.0

Given the composition of Rock R, which sample is most likely Rock R?

A. Sample A
B. Sample B
C. Sample C
D. Sample D

Why this is a hard question → It requires you to combine information from multiple tables and it has multiple steps; if you get one wrong, the next step will also be wrong.

Once again, you don’t need any information from the passage to answer this question. All you need is Table 1 and the table in the question.

There’s a clue in the question: Given the composition of Rock R. So look back at Table 1 above: this is the breakdown of what Rock R is made of.

What do you know?

• The mass percentage of different components in Rock R.
• The mass of quartz in different mystery rocks.
• The mass of the mystery rocks (50g).

What do you want to know? And how can you translate that into something that’s answerable with your available data?

• Which mystery rock is likely Rock R → which rock has a composition that matches the composition of Rock R?

Because we only know the mass of quartz in the mystery rocks, that’s what we’ll have to go on. We can ignore the data for all the other components. Based on Table 1, Rock R is 72.5% quartz.

Which of these 50g mystery rocks could be 72.5% quartz? They’re all 50 grams, so the mass of quartz in the correct one would be 0.50 • 72.5 = 36.25 grams.

B is the closest match for the amount of quartz in Rock R, so it’s the most likely answer.

Answer: B.

Questions like this can be time-consuming, and since they have multiple steps, it’s easy to get confused. If you need to brush up on the test content or improve your time management or test-taking strategy, an experienced tutor can be a big help.

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Research Summaries

The hardest types of research summaries questions might: 

• Throw a lot of data and information at you
• Bury key information in the middle of that information dump
• Require you to extrapolate based on the information you have (for example, if you’re told that only one thing was changed in Experiment 2, you know that everything else remained the same)

The next question is about the information set below.

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#8: Predicting Results

This question is about the “Research Summaries” information set above.

Based on the results of Experiment 1, if Experiment 2 were repeated except that all the N. davidi were fed Diet R, would the average SGRs more likely have been lower or higher for each group?

F. Lower; on average, N. davidi fed Diet R had an SGR 0.05 percent/day less than those fed Diet T.
G. Lower; on average, N. davidi fed Diet R had an SGR 0.10 percent/day less than those fed Diet T.
H. Higher; on average, N. davidi fed Diet R had an SGR 0.05 percent/day greater than those fed Diet T.
J. Higher; on average, N. davidi fed Diet R had an SGR 0.10 percent/day greater than those fed Diet T.

Why this is a hard question → It combines a lot of different tricky factors: prediction, multiple steps, and science jargon.

For these questions, it can be tempting to read the passage in detail and try to understand the whole experimental setup. Don’t do that! 

For this classic type of ACT Science question, which asks you to compare two experiments and predict the likely outcome, you do not need to understand the experiment in detail.

You just need to identify how the experiment is changing and what effect that will likely have based on the data.

• What’s changing in Experiment 2? The shrimp are getting fed a different diet.
• What do we want to know? How this will affect the SGR. (We don’t have to know or care what SGR means.)
• What do we already know? The average SGR for groups of shrimp on different diets.

Now, we can combine all that into an approach: look at the SGR for the new diet and determine whether it’s higher or lower than the other diets to predict whether the new diet will make SGR go up or down.

Based on Table 1, Diet R leads to an SGR of 0.65 percent/day. That’s higher than two of the three other diets, although it’s not the highest. So if we switch all the shrimp to Diet R, we can expect SGR to go up on average. 

Now, use the process of elimination to choose between answers H and J. The only difference is something you can easily verify in Table 1: how much bigger is SGR on Diet R than on Diet T?

Table 1

Diet	Average SGR (percent/day)
Q	0.45
R	0.65
S	0.75
T	0.55

On Diet R, the SGR was 0.65 %/day. On Diet T, the SGR was 0.55 %/day. So 0.65-0.55 = 0.10 %/day.

Answer: J.

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Conflicting Viewpoints

The hardest types of conflicting viewpoints questions might: 

• Present a lot of text, which can make it hard to find the information you need
• Be time-consuming, because, unlike many other question types, they often require you to read a lot of the text to get to the right answer. (It’s often worth saving these for last.)

The next question is about the information set below.

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#9: Summarizing Arguments

This question is about the “Conflicting Viewpoints” information set above.

Which student would be most likely to agree that while the cylinder was partially submerged, the scale was supporting the entire weight of the cylinder?

F. Student A
G. Student B
H. Student C
J. Student D

Why this is a hard question → It requires you to skim and synthesize a lot of information.

Note that for this question, you don’t need to decide which student is right! You only need to decide who would be likely to make this argument.

Your strategy here is to figure out the different ways this claim might be phrased and then skim the students’ arguments to find a match.

If the scale is supporting the entire weight of the cylinder, then that would mean the teacher’s hand is supporting none of the weight.

Skimming the students’ arguments for a match, Student C is the one arguing that the hand is supporting none of the weight. That means Student C would probably agree that the scale is supporting all of the weight.

Answer: C.

Questions like this require you to have a solid grasp of ACT test-taking skills. If you need to brush up on the test content or improve your test-taking strategy, an experienced tutor can be a big help.

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Key Strategies for ACT Science

A few key strategies can help you with almost any ACT Science question.

#1: Start with the questions (and answers).

You simply don’t have enough time on the ACT to read every word carefully. Instead, read the questions and then go looking for the specific information you need.

#2: First, determine what information you need.

Ask yourself:

• What do I already know?
• What do I want to know?
• How can I get the information I want out of what I already have?

#3: When you have to read the passage, skimming is usually enough.

Keep the key word or information you’re looking for in mind. Then skim the passage until you find it. Read that relevant information more closely and leave the irrelevant background.

#4: Circle or mark the relevant information.

It’s easy to misread a chart or graph when you’re going quickly. Circle the information that you’re basing your answer on. That will make it easier to check your work.

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Next Steps

If you’re aiming for a top ACT score, or even a perfect score, you’ll need to be able to answer the hardest questions. The Science section might be optional now, but a strong Science score can only boost your college application.

The good news is that it’s very possible to raise your score. That’s because, as you’ve seen, ACT Science relies heavily on predictable questions. Once you learn the strategies to crack those questions, you can handle even the hardest ones.

If you’re interested in customized one-on-one tutoring support from an expert ACT tutor who can help you learn those strategies, schedule a free consultation with us. Our tutors are top scorers themselves, and they can help you with these more advanced concepts and strategies.

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