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.
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?
- A. 25
- B. 30
- C. 35
- 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.