Patterns are based on the relationships between the variables in an experiment. On ACT Test Day, pattern questions usually appear with Research Summaries and Data Representation passages and ask about minimum or maximum levels, points of change, and/or direct and inverse variation.
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 try a sample question!
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.
A final word of warning: experiments or research is explained numerically in a table or graph, and those numbers could be explained in millimeters in one table and meters in another. If you accidentally count the millimeters as meters, you could be in big trouble. Pay attention to those abbreviations and keep track of the units! Don’t let them try to fool you. 🙂