Question 158·Medium·Command of Evidence
A line graph titled Cooling of Heated Water shows the temperature (in degrees Celsius) of water in three identical cups over 20 minutes. One cup is left unwrapped, one is wrapped in aluminum foil, and one is placed in a foam sleeve.
To study how different coverings affect energy transfer from a hot object to its cooler surroundings, researchers poured heated water into three identical cups and immediately applied the three different treatments. The cups were left in the same room, and the water temperature in each cup was recorded at regular time intervals. The researchers concluded that the foam sleeve slows the transfer of thermal energy from the water more effectively than aluminum foil or no covering.
Which choice best describes data in the graph that support the researchers’ conclusion?
For command-of-evidence questions tied to a graph, first translate the conclusion into a specific pattern you should see in the data (here, foam should be warmest at the same times). Then check the graph for the clearest, most consistent support for that pattern across multiple time points. Finally, pick the option that states that full comparison without adding claims the graph does not show.
Hints
Restate the claim in your own words
The claim is comparative: one covering should keep the water warmer than the others, not just “warm” by itself.
Look for the strongest repeated trend
Scan the graph at 5, 10, 15, and 20 minutes. Which treatment’s line is consistently highest?
Prefer evidence that compares all groups
The best evidence should mention foam relative to both foil and the unwrapped cup, not just one comparison or a single temperature change.
Step-by-step Explanation
Identify what the conclusion requires
The conclusion compares treatments: the foam sleeve should keep the water warmer than both aluminum foil and no covering if it slows thermal energy transfer the most.
Find the comparison in the graph
Look at the temperatures for all three cups at the same times (5, 10, 15, and 20 minutes) and see which line is highest.
Choose the option that matches the strongest pattern
The foam-sleeved cup is highest at every time shown after 0 minutes, directly supporting that foam slows cooling more than foil or no covering. Therefore, the best choice is: At each time shown after 0 minutes, the cup in the foam sleeve has the highest water temperature compared with the foil-wrapped and unwrapped cups.