Concept 3

Compare datasets across conditions and interpret differences.

Compare values at the same condition before deciding which dataset is greater or changes more.

Core Idea

Compare matched points, not unmatched impressions. Use the same x-value or condition for both datasets before deciding which is greater or changes more.

Understanding

ACT Science often shows two lines, two tables, or several conditions from one experiment. The safest comparison is always a matched comparison.

  • Match the condition first: same time, same temperature, same trial, or same sample.
  • Compute the difference if needed: do not trust visual spacing alone.
  • State the comparison precisely: which condition is greater, by how much, or in which interval the gap is larger.

A correct comparison uses the same reference point for both datasets.

Step by Step

  1. Find the single condition named in the question.
  2. Read both datasets at that same condition.
  3. Subtract or compare the two values directly.
  4. Check whether the answer choice keeps the comparison tied to that matched condition.

Misconceptions

  • Comparing one condition from Dataset A with a different condition from Dataset B.
  • Choosing the line that looks steeper overall when the question asks about one specific point.
  • Calling two datasets equal because they cross at some other location.
Question

Worked Example

Table 2 shows bacterial colony count after 12 h in two cultures: pH 5 = 18 colonies and pH 7 = 26 colonies. According to Table 2, which statement is supported?

Select an answer to see the explanation