ACT® · Science: Interpretation of Data (13-17 items)
Combining Two or More Simple Presentations (IOD 501)
Some questions hand you two tables instead of one, and you have to link them through whatever label or variable they share. Once matched correctly, the lookup itself is just as quick as a one-table question.
A two-table question feels harder because you can't just read one number off one chart. But the extra work is small: find the shared identifier or variable, locate your value in the first table, then carry it into the second table to classify, convert, or look it up. The reasoning is the same single step you'd use with one table; you're just doing it twice, so it costs seconds, not minutes.
The key move is matching correctly. Tables often list the same items in different orders, alphabetical in one, chronological or by measurement in another, so row 3 in Table 1 is rarely row 3 in Table 2. Always match by the label both tables carry: a site name, a sample ID, a city, a date. Once matched, pull the number you need from one table and check where it falls on the scale, range, or category given in the other. If the shared variable is measured in different units across the two tables, convert first; a mass of 450 grams and a table scaled in kilograms are the same fact, just dressed differently.
This skill sits right next to reading a single table or graph: everything you already know about finding values, bands, and trends still applies, you're just applying it across two sources instead of one. It also leads naturally into questions that mix a table with a graph, or ask you to reconcile results from two different experiments, where the same rule holds: match by what's shared, not by position on the page.
Key terms
- Shared label
- The common identifier, like a name, site, or sample ID, that lets you link the same item across two tables.
- Lookup table
- A table that maps ranges of one variable to a category or rating, used to classify a value found elsewhere.
- Unit conversion
- Rewriting the same measured quantity in different units, such as grams to kilograms, so two tables can be compared.
- Interpolation
- Estimating a value that falls between two listed entries in a table or on a scale.
Watch it explained
- How it worksHow do you use a scale printed in one table to categorize a number pulled out of another table?
- Common mistakeWhy isn't matching two tables a matter of lining up their rows in the order they happen to be printed?
- Worked exampleFind the hazard rating of a 6.2 magnitude quake when one table lists magnitudes and another maps ratings.
- Going furtherWhat changes when the variable shared by two tables is recorded in different units in each one?
Check yourself
End of topic.