### Posts Tagged ACT science questions

#### Understanding “Variables” on the ACT

Time management is crucial for great scores on the ACT Science Test. Since you only have about 5 minutes per passage, that’s less than one minute per question. Spend long enough on each passage to identify just the main information, and don’t get bogged down with the confusing details. Ignore any unknown terminology and spend most of your time on the presented data and the variables.

A “variable” in math is a placeholder for an unknown. In ACT Science, this takes on a slightly different meaning and is used to describe the factors in an experiment.  Independent variables are factors that are controlled by the scientists. Did the scientists increase the heat in the experiment? Did they add or remove pressure? If the scientists have control over the variable, it is independent. Dependent variables are factors that the scientists observe changing. This is what the look for and how they record data — but they don’t control it.

You will also need to know direct variation and indirect variation. Direct variation occurs when two variables change in the same way over time. If Column A increases and Column B increases at the same time, we can say that the two columns vary directly.  If when Column A increases, Column B decreases, there is an indirect (also called inverse) variation between the two elements. In the real world, think of a pizza and the number of slices eaten. The weight of the pizza is inversely proportional to the number of slices eaten. That means that as more and more slices are eaten, the pizza weights less and less. In ACT Math, you may see direct and indirect variation in expression such as “y varies directly as x” or “y is directly proportional to x.” That means you can use the equation y = kx, where k is the constant of variation.

To understand the variables, look at the presented figures. Ask yourself: what does the figure tell me? What are the units of measurement? What changes, and when? In order to answer ACT Science questions correctly, you will need to pinpoint the relationships between the variables. Don’t try to memorize. Always go back to the data to find the correct answer. All of the information you need to get the questions correct are found the in passages, we just have to know where to look!

Much of the ACT Science data will be presented on graphs. Every graph has an x-axis and a y-axis. Pay close attention to the labels. The independent variable is most often found on the x-axis. When faced with multiple graphs, typically only one thing has changed. This is usually done by scientists to examine the results when a single variable is altered. If the scientists changed more than one variable, it usually doesn’t help them draw conclusions, since they wouldn’t know which change created the new results.

Remember to do the following for Data Interpretation and Research Summaries passages on Test Day:

1. Find the Purpose, Method & Results for each experiment.
2. Examine the data carefully, and look for the variable relationships.
3. Go back to the passage for the correct answer.

Follow these steps on your next ACT Science passage on Grockit and you’ll soon be mastering even the most complex experiments!

#### ACT Science – 3 Tips to Get Better Scores

The ACT Science Test is a lot easier than you think (after all, it’s basically an open book test)! Even if your knowledge of Science is limited, you can still get better scores through discipline and hard work. On Test Day, the ACT Science Test will always be the fourth test you’ll take. It will have 7 passages and you’ll have 35 minutes to complete them.

Find out other great ACT science strategies here!

1. Practice your pacing! Don’t wait until two weeks before your test to get started. You will only have about 5 minutes per passage, so you may want to start by only doing 5 passages, allotting 7 min per passage. Once you can confidently do 5 passages with reasonable accuracy, work your way up to 6 and then 7. If you have a limited time to study and your accuracy significantly drops after 5 passages, just stick to 5 on Test Day. Better to do 5 really well and guess on 7 than to do all 7 sloppily.
2. Always refer back to the passage. You won’t be able to memorize the information presented in the passages; it’s too overwhelming. Read the passages to understand the gist and the data that is presented, but also move back to the passage to locate the information you need to answer. Memory alone will not suffice, and you may find it helpful to jot down a few short notes on each passage. Drawing arrows and circling important info is also a great idea
3. Adopt a strategy for each of the 3 formats. ACT Science Test passages come in three forms: Data Representation, Conflicting Viewpoints, and Research Summaries. You will need to modify your approach slightly for each one. Data Representation focuses mostly on charts, graphs, and tables, so you will need to practice identifying trends and understanding the layout of variables. Conflicting Viewpoints typically has no diagrams and is more like the paired passages you might remember if you took the SAT. Research Summaries describes one or more experiments. You will need to understand the Purpose, Method, and Results for each experiment, and know what the similarities and differences were between them. Don’t treat these 3 formats all the same – they are each quite unique!

Set a timer the next time your work on an ACT Science practice test, and see if you can stick to these checkpoints. This is the ideal timing for the actual exam:

:00 … Set the clock and begin!

:05….Finish gridding in the answers for Passage 1

:10….Finish gridding in the answers for Passage 2

:15….Finish gridding in the answers for Passage 3

:20….Finish gridding in the answers for Passage 4

:25….Finish gridding in the answers for Passage 5

:30….Finish gridding in the answers for Passage 6

:35….Finish gridding in the answers for Passage 7 (make sure you can do this before time is called!)

Ready to practice on some ACT Science passages? Join a game in the Grockit ACT lobby to work with other ACT students. You will start to see the three question-types, Data Representation, Conflicting Viewpoints, and Research Summaries. Practice identifying them with other students and share strategy tips!

#### Recognizing Patterns on the ACT Science Test

To get a great score on the ACT Science Test, you will need to understand the trends in presented data and be able to predict patterns for these trends as they apply to new situations. On ACT Test Day, pattern questions usually ask about the following: minimum or maximum levels, points of change, or direct/inverse variation.

Test your ACT science skills with this practice question today!

The minimum level is the smallest data point for a given entry. The maximum level is the largest data point for a given entry. Point of change occurs when preceding data has a different relationship to the remaining data. Direct variation means that two items are directly proportional: when one increases, the other increases. Inverse variation means that two items are indirectly proportional: when one increases, the other decreases. Sometimes you will be given a graph and asked to extrapolate, or to extend the graph beyond the values on the axes to find an x-value or a y-value that is out of the given range.

Let’s look at an example ACT example Pattern question from Grockit’s database:

Experiment 2 is repeated at a temperature of 45°C. Assuming that the results from both experiments continue to hold true, what is the most likely solubility (in g solute/100 g water) of Ca(NO3)2 at 800 torr?

1. A. 25
2. B. 30
3. C. 35
4. D. 40

The answer is D. Overall, since the solubility of all solids in Experiment 1 increases with increasing temperature, the logical pattern is that the solubility of Ca(NO3)2 would increase as its temperature increases. Initially, Experiment 2 was run at 25°C. Running it at 45°C should increase Na2HSO4’s solubility from the level of 35 g/100 g H2O. Pressure had no real effect on the solubility of any of the solids in Experiment 2.  Let’s look at a second example:

Table 1. Relative abundances of the elements in the Solar System

Element          Atomic #      Abundance (%)

H                      1                91.03

He                    2                  7.24

C                      6                  0.41

N                      7                  0.11

O                      8                  0.79

Ne                   10                 0.10

Mg                   12                0.05

Si                     14                0.05

ALL OTHER ELEMENTS >14     < 0.05

According to Table 1, as the atomic number increases from 8 to 9 to 10, the abundances:

A            Decrease, then increase

B            Increase, then decrease

C            Decrease only

D            Increase only

Note that the last line of the table indicates that the abundance of element 9 must be less than 0.05%. The abundance therefore decreases from 0.79% at element 8 to <0.05% at element 9, then increases again to 0.10% at element 10. The answer is A.

Sometimes the pattern will be more visual than numerical:

In Study 1, if the electrical activity of the resting volunteer had been measured for an additional 1 second, the voltages would have varied between approximately:

A            -5 and +5 microvolts

B            -25 and +25 microvolts

C            -50 and +50 microvolts

D            -100 and +100 microvolts

From 0 to 1 second, we can see the range was always between +25 and -25. There is no reason to assume that there would be any change if we were to continue this experiment for an additional second. The answer to this pattern question is B.

Need more help? Grockit’s ACT Tutors conduct private lessons via Skype to help you build your ACT strategy, customize your study plan, and to help answer he toughest ACT practice questions. Find out more on the Tutoring tab in the Grockit lobby, or go ahead and join a Group Game to practice with other ACT Students!

#### ACT Science: How to Understand Procedure in an Experiment

For some ACT Science questions, you will need to be able to answer questions on how certain experiments are set up. These questions can appear in any of the three Science passages: Data Representation, Research Summaries, and Conflicting Viewpoints, but are much more common in Research Summaries. To improve your scores on Procedure questions, and achieve a higher ACT Science score overall, it’s important to extract the set-up from any experiment mentioned BEFORE moving on to the questions. Learn to take notes on your scratch paper while you work in Grockit’s group games, just as you would on the actual ACT test.

Let’s examine a Research Summaries passage from Grockit’s question bank:

Soap molecules often consist of long chains of hydrocarbons ending in a negatively charged ion.  In water, the soap molecules form clusters called micelles. Soaps are able to remove dirt particles from surfaces by trapping them in the centers of the micelles.

Experiment 1

A science fair student designs an experiment to measure the cleaning power of sodium oleate, a chemical that can be used as a soap.  In the experiment, eight white T-shirts were stained with either dirt or ketchup.  After the shirts were cleaned under varying conditions, the student rated how visible the stains were.

Experiment 2

The student wishes to demonstrate that the cleaning action is due to the oleate, and not to the sodium.  Accordingly, the student measures the cleaning power of potassium oleate, using 4 scoops of the soap to clean a T-shirt stained with ketchup and a T-shirt stained with soil, to show that the same results are obtained under these circumstances.

Here is how our scratch paper notes might look:

Experiment 1 –

1. Purpose: to measure sodium oleate
2. Method: 8 stained shirts (dirt or ketchup), then cleaned in various conditions
3. Results: student rated visibility of stains

Experiment 2 –

1. Purpose: to measure oleate
2. Method:  2 stained shirts (1 ketchup, 1 dirt), 4 scoops of potassium oleate to achieve same results as Exp. 1

We must pay close attention to what was similar and what was different in the procedure. Both experiments dirtied shirts, then cleaned them. However, the number of shirts stained was different in each, and Experiment 2’s shirts were only cleaned to the extent that they matched the level of dirtiness left on the shirts from Experiment 1.

Here is how a sample “Procedure” question might look. We can identify it as such because it explicitly asks about the set-up of the experiments.

Experiment 2 differed from Experiment 1 in that:

A            The amount of soap was varied only in Experiment 1

B            The stain was varied only in Experiment 1

C            The amount of soap was varied only in Experiment 2

D            The stain was varied only in Experiment 2

Another way to think of this question is: “what changed between the experiments?” Looking at our notes, we can see that the cleaning solution changed (sodium oleate to potassium oleate), the number of shirts changed (from 8 to 4), and what was specifically being measured changed (in Exp. 1 it was the visibility of the stains, in Exp. 2 it was how many scoops to achieve the results of Exp. 2).

We can quickly eliminate B and D, since the stains were different (ketchup and dirt) within each experiment. Since Experiment 2 measured how much soap was needed to achieve the results of Experiment 1, then it’s likely different amounts were needed depending on the severity of the stain. In Experiment 1, it is implied that all of the shirts were uniformly washed with the same amount of soap, but the conditions of the washing were modified.

Therefore the answer is (A). For more practice with Procedure in an Experiment questions, message one of the Grockit ACT tutors to schedule a 1-hour ACT Science lesson! Check out our statistics and choose the right tutor for you!

#### ACT Science: Strengthen Hypothesis

Science questions on the ACT may ask you if a piece of evidence, always supplied in the reading passage or in a chart, graph or table, supports and strengthens the hypothesis put forth in the passage. Answering strengthen hypothesis questions require you to identify a hypothesis and understand how data can strengthen or weaken that argument. Although this question type can be time consuming to answer, getting the proper test prep at Grockit will help you master strengthen hypothesis questions. So will these tips and strategies:

• Read the passage before looking at the questions. Reading the questions first, especially if there’s a hypothesis strengthening question, may mislead you when reading the passage and examining any charts, graphs or tables.
• Read the first paragraph very closely. It’s very likely that the passage’s hypothesis will be explicitly stated in the first paragraph, maybe even the first sentence. Make sure you understand what it is.
• Read for the main idea. For any reading passage, you should be reading for the main idea, or purpose. If you do this, you should be able to identify the passage’s hypothesis.
• Don’t read for the details. It’s a waste of time memorizing details for strengthen hypothesis questions. You’ll be asked about a specific detail, and at that point go back in the passage or to the correct chart, graph or table and find the information you need.
• Skip questions you don’t know. Since you’re ACT score is based off of how many questions you answer correctly, move on if a strengthen hypothesis has you stumped.

Try this ACT science question for more practice!

Now let’s use these tips/strategies on a sample question:

Stars often form in large groups.  For instance, an “open cluster” such as the Pleiades may contain hundreds of stars that were formed at approximately the same time (and are thus the same age). Even larger “globular clusters” may contain a million or more stars of approximately the same age.  By observing clusters of increasing age, astronomers are able to see how the brightness and temperatures of stars change as they age.
Shortly after a group of stars forms, a plot of their brightness versus their color shows that they form a diagonal line called the “Main Sequence.” The bluest stars, are the brightest, and the reddest stars are the dimmest.  (Star colors are divided into a series of “spectral classes” – O, B, A, F, G, K.  A star’s brightness is expressed as an “absolute visual magnitude,” with the dimmest stars having the largest magnitudes.)
After millions of years, the bluest stars in the cluster begin to swell into “giant” or “supergiant” stars, and they become redder.  Thus, they no longer lie on the Main Sequence line.   As the cluster gets older, the same process happens to redder and redder stars.

Astronomers observing a nearby galaxy have measured the position of the “turnoff” in 25 globular clusters.  If the turnoff occurs at the same spectral class in different globular clusters, those clusters must be of approximately the same age.  Furthermore, if most of the clusters in a galaxy are of similar ages, the galaxy itself may be of that age.  Figure 2 shows the number of clusters with turnoffs in each spectral class.

Does Figure 2 support the hypothesis that most of the galaxy’s globular clusters are of similar ages?

1. No, Figure 2 shows that the clusters in the galaxy have different turnoffs, and thus different ages
2. No, Figure 2 shows that the turnoffs of the clusters vary from A to K in spectral class, and these clusters thus vary widely in age
3. Yes, Figure 2 shows that most of the clusters in the galaxy have a turnoff in spectral class G, and are thus similar in age
4. Yes, Figure 2 shows that all of the clusters in the galaxy have a turnoff, and are thus similar in age

There are several things you need to know to figure out if Figure 2 supports the passage’s hypothesis. First, you need to know the hypothesis, which is “Stars often form in large groups.” Now, we have to examine Figure 2 to figure out what information it’s relaying. The y-axis shows an increase in the number of clusters as we move up; the x-axis labels the different spectral class of “turnoff” for the star. What we then see is that Figure 2 shows the highest number of clusters in the G class of turnoff, meaning that the scientists’ hypothesis is correct. If we examine the answer choices, we can eliminate A and B since they misinterpret the question. C looks correct since the chart shows most of the clusters in spectral class G and the passage told us this meant they were of similar age. And D doesn’t seem to mention any points mentioned in the passage or chart. We’re left with C as the correct answer.

By following the tips and strategies above, you’ll be able to solve any strengthen hypothesis question on the ACT . Just make sure you get plenty of test prep, going to Grockit to fully prepare yourself for test day. You may be surprised at how much fun you’ll have preparing for the ACT .

Need more help with ACT science questions? Get personalized tutoring in live online sessions with an experienced expert instructor.

#### ACT Science – Conflicting Viewpoints

The second type of ACT Science passage you will see on test day is Conflicting Viewpoints. In these passages, several different viewpoints or hypotheses will be presented on a specific scientific phenomenon. The first few paragraphs will describe the phenomenon and the remaining paragraphs will outline each student or scientist’s viewpoint. These passages typically contain more words than Research Summaries and Data Interpretation passages so your Reading skills will definitely be useful here! Let’s look at some tips for handling Conflicting Viewpoints:

1. Identify the phenomenon. This is usually located in the very first paragraph. What is the main subject the students or scientists are studying? This frequently will include unfamiliar scientific terminology but don’t panic! Any new vocabulary will be defined by the passage. Locate and underline the phenomenon before you move on to the viewpoints.

2. Understand the basic theories. Each student or scientist will have a basic theory in regards to the phenomenon. This is usually the first sentence underneath their name. Try and put yourself in each scientist’s shoes. Ask yourself, how are the basic theories different? How are they similar, if at all? Underline these as well so you can easily reference them later.

Test your skills with this Grockit ACT Science question!

#### ACT Science – Research Summaries

The ACT Science section can cause a lot of unnecessary worry among test-takers. However you can still receive a strong score even if you aren’t a budding Albert Einstein. Careful reading and note-taking (the same skills you use for Reading Comp!) are enough to answer most questions. Remember – the answer has to be based on the information in the passage. You just have to know where to look!

The ACT Science Test will always be the fourth test you’ll take. It will have 7 passages and you’ll have 35 minutes to complete them. That’s about 5 minutes per passage so moving confidently through this test is essential! It takes practice to gain confidence in interpreting data and understanding the meaning of unfamiliar vocabulary. Luckily, you already have all of the skills necessary to do this from your high school Science classes.

Let’s take a look at the first of three types of Science passages you’ll see: Research Summaries.

Try this ACT Science practice question from Grockit!