Answering Science Questions without Science

Sometimes you can answer Science questions based purely on the units in the answers.  In the following question, knowing what S is or what Table 2 says is unnecessary.

34. Lightning strikes can occur when air between the ground and the base of a storm cloud is exposed to an electric field stronger than S for air. Suppose a certain storm cloud's based is 300m above the ground the ground. Based on Table 2, approximately what minimum voltage would be present between the storm cloud's base and the ground immediately before a bolt of lightning from this storm cloud strikes the ground? 

F.  300,000 mm x 3.13 kV/mm 
G. 300.000 m x 3.13 kV/mm
H.    300 mm    
     3.13 kV/mm
J.       300 m     
    3.13 kV/mm

December 2015 (72E)

The question asks for "minimum voltage." Therefore, the unit of the answer will be have to be some sort of voltage, and the only unit of voltage is kV.. Get rid of H and J because kV is in the denominator, so the unit in those will be 1/kV. Get rid of G because it has different length units in the  numerator (meters - m) and the denominator (millimeters -mm), and they won't cancel out. The only answer in which the length units will cancel, leaving a voltage unit, is F.

The Perfect Tense on the ACT

A. John took the ACT.
B. John has taken the ACT.


Choosing between between the present perfect tense (“has taken”) and the past tense (“took”) isn't always easy. Deciding on the past perfect tense (“had taken”) isn't any easier. According to Grammerly, “The present perfect tense refers to an action or state that either occurred at an indefinite time in the past (e.g., we have talked before) or began in the past and continued to the present time (e.g., he has grown impatient over the last hour).” That doesn't really clear things up though.


The fact of the matter is that there is often little basis to prefer one over the other. In the example above, either choice satisfactorily answers the question, “Did John take the ACT.” The good news is that the ACT rarely presents a straight choice between the perfect tense and the past tense—perhaps because there are so many cases when either one would do the trick. Most of the time when both the perfect tense and the past tense among the choices, there is some other issue that determines the correct choice.

The men combined their skills, organized a group of investors, and remains in business for more than fifty years.

5. A. NO CHANGE
    B. has remained
    C. have remain
    D. remained

April 2015 (73G)

If the choice were between “have remained” and “remained,” it might be tough call. but happily, the student is not required to make that decision. A is incorrect both because “remains” is singular while the subject of the sentence, “men,” is plural and because “remains” is present tense while the other verbs in the sentence, “combined” and “organized,” are past tense. B is incorrect because “has” is singular. C is incorrect because the perfect tense requires the past participle, “remained.” Thus D Is correct. Whenever, the perfect tenses and the past tenses are among the answer choices to an English question on the ACT, the first thing to do is to look for something else going on. The fact that there is so little difference between the past tense and the perfect tense can even help you to the correct answer when other rules are being tested.

It was exhausting to spend every day in the hot summer temperatures while pretending to be a person whom had lived in a different country and century.

25. A. NO CHANGE 
      B. who were to live 
      C. whom lived 
      D. who lived 

April 2015 (73G)

If you know your “who” or “whom” rules, you know that the answer is D. If you aren't sure about those rules, consider how little difference there often is between “lived” and “had lived.” Since the ACT rarely requires you to make that choice, it is likely that both A and C are wrong.

On those occasions when there is a direct choice between perfect tense and past tense, going for consistency will usually produce the correct response.

Worse yet, there's no going back; the old hot water pipes have been ripped out, and a jagged four-foot hole in the roof has turned into an unplanned and precarious skylight. 

25. A. NO CHANGE 
      B. was turning
      C. turned
      D. would have turned

May 2002 (55C)

The first thing to check when verb tenses are in play is the surrounding verbs. Here we have another verb in the sentence in the past perfect tense ("have been"), so go with A to be consistent.

There are some cases where there is a clear difference in meaning between the perfect tense and the past tense.

A. After John's wife left him, he went crazy. 
B. Since John's wife left him, he has gone crazy. 

A describes an event that occurred in the past followed by another event that occurred in the past. It says nothing about John's current state of mind. B describes an event that occurred in the past followed by a condition that continues to the present. If the ACT requires a choice between the perfect tense and the past tense, it is likely to be this type of situation. 

While some sculptors suggest the magnitude of an event by presenting larger-than-life figures, Lin relies on more understated methods to suggest matters of great significance. Since the unveiling of the Vietnam Veterans Memorial, Lin has applied this approach in different parts of the country and to different areas of United States history. 

51. A. NO CHANGE 
      B. will apply 
      C. applied 
      D. applying  

April 2005 (60E)

Here is an event that occurred in the past, the unveiling, followed by an ongoing practice by the sculptor. The correct answer is A. When faced by the perfect tense on the ACT, the student should first look for what else is changing in the answer choices. There will usually be other issues that decide the answer. On occasion, however, the ACT does test the perfect tense directly.\

Blogging About the ACT and SAT

I have been tutoring for the ACT and the SAT for the last three years. For the last few months, I have been answering students' questions from time to time on reddit at r/ACT and r/SAT. As the same questions tend to get repeated, I thought I would post some of my answers on a blog. Feel free to ask questions.