Ability (Reasoning)
What the Ability subtest asks
The TACHS Ability section measures reasoning rather than school content. It mixes verbal and nonverbal items: analogies, odd-one-out classification, letter and number series, and pattern logic in sequences or grids. The tested skill is spotting the rule quickly and applying it exactly.
Core rules
- For analogies, state the relationship as a phrase: "a thermometer measures temperature." Then apply the same phrase to the second pair.
- Keep the direction of the relationship; part-to-whole is not whole-to-part.
- For classification, name the category three items share and say why the fourth fails.
- For series, check differences, then ratios, then alternating patterns (two interleaved sequences).
- For grid patterns, test rows and columns separately; the rule usually holds across each row and down each column.
- Eliminate choices that are related but use the wrong relationship.
Worked example
Analogy: Thermometer is to temperature as odometer is to ______. Relationship: a thermometer measures temperature; an odometer measures distance traveled. Answer: distance. A tempting wrong choice is "speed"-related to odometers, but speed is measured by a speedometer. The relationship must match exactly, not merely be associated. Number series: 2, 6, 12, 20, 30, ______. Differences are 4, 6, 8, 10, increasing by 2, so the next difference is 12, giving 42. The terms also follow n times (n + 1): 1x2, 2x3, 3x4, and so on.
Traps that cost marks
- Reversing the analogy's direction.
- Accepting the first plausible rule in a series without testing it against every term.
- Choosing a word from the same topic but with the wrong precise relationship.
- Overlooking a second, interleaved pattern in a long series.