To maximize the rate of thermal energy transfer into the skillet, John should put the skillet on the large burner.
From the data provided, the skillet on the large burner reached a higher final temperature (88°C) compared to the skillet on the small burner (67°C) over the same time period. This indicates that the large burner is capable of transferring thermal energy at a faster rate, resulting in a quicker increase in the skillet's temperature.