ACT® · Science: Scientific Investigation (6-11 items)
Which Experiment Used a Given Tool or Method (SIN 405)
When a question names a specific instrument or method, the answer lives in the methods section of each experiment, not in the data tables or results. Scan each write-up for that exact name and pick the one that matches.
A question that names a tool, like a spectrophotometer, a thermocouple, or a centrifuge, is really asking you to go find where that word appears in the passage. It is not asking you to interpret a graph or compare results. So the fastest and most reliable move is to skip the data and read only the short methods description under each experiment, looking for that exact word or a clear description of it.
The sweep works because passages with multiple experiments usually change one or two things between them: the organisms, the time scale, or the instruments used. If three experiments are described and only one mentions measuring temperature to a tenth of a degree, that precision is a strong clue a thermocouple was used, even if the word never appears. Other experiments might use a thermometer or no temperature measurement at all, so checking each write-up in order, rather than jumping to whichever one looks familiar, keeps you from picking the wrong one.
This skill sits right next to comparing two designs that share a tool but use it differently, like one experiment reading a spectrophotometer once at the end of a run and another reading it every few minutes throughout. There, naming the tool is not enough. You have to match how it was used, which ties this topic to the broader skill of comparing experimental designs side by side rather than just locating instruments.
Key terms
- Methods section
- The part of an experiment write-up describing what was done and with what tools, separate from results or data.
- Instrument sweep
- Reading through each experiment's methods in order to find the one mentioning a named tool.
- Thermocouple
- A sensor that measures temperature, often precisely, by generating a voltage from a temperature difference.
- Spectrophotometer
- An instrument that measures how much light a sample absorbs, often used to track chemical concentration.
- Design comparison
- Judging not just whether two experiments used the same tool, but whether they used it the same way.
Watch it explained
- How it worksHow do you sweep three experiment write-ups for the one that mentions a particular instrument?
- Worked exampleFind which of three experiments used a thermocouple when only one reports temperatures to a tenth of a degree.
- Going furtherWhat changes when two experiments both used a tool and only one used it the way a question describes?
Check yourself
End of topic.