Similarities and Differences Between Experiments (SIN 404)

Passages with multiple experiments are built around a comparison. The experimenters usually kept almost everything the same on purpose, so that the one thing they changed is the one thing that can explain a difference in results. Your job is not to read every number again. It's to build a mental table: rows are variables like temperature, pressure, concentration, time, apparatus; columns are Experiment 1, Experiment 2, maybe Experiment 3. Scan down the rows. Most will match. The row or rows that don't match are where the actual scientific question lives, and where the answer choices will cluster.

Shared equipment is a trap. Two experiments can use the exact same reaction vessel, same balance, same water bath, and still be asking completely different questions, because what matters is which quantity was deliberately varied, not which tools sat on the bench. A shared setup is often mentioned just to prove the comparison is fair, not to suggest the experiments test the same thing. Read past the list of shared gear to find the variable that was actually changed.

This skill sits right next to identifying controls and variables within a single experiment, and next to the newer engineering and design items that ask you to judge whether a design is sound. Once you can spot the single changed variable between two trials, you can also judge what a result does and doesn't prove. If two experiments differ in only one way and the outcome changes, that one variable is the likely cause. If they differ in two ways at once, the passage usually wants you to recognize that no single cause can be pinned down from that comparison alone.