You’ll probably wonder what an experiment involving a bucket of ice has to do with teaching ESL but bear with me. 
In The Power of Moments by Heath & Heath, the authors discuss an interesting psychological experiment in which participants were subjected to two different versions of an unpleasant experience.
The first trial had subjects submerge a hand in 57-degree (14°C) water for 60 seconds.
The second trial had participants submerge the other hand in 57-degree water for 60 seconds yet they then kept their hand underwater for an additional 30 seconds, during which time the temperature was raised to 59 degrees (15°C).
Next, participants were asked “Would you rather repeat the first trial or the second?” Amazingly, two-thirds of the participants chose to re-do the second trial, even though they were exposed to uncomfortably cold temperatures for a longer time. Researchers concluded that participants chose the second, longer trial because they preferred the memory of that second trial or disliked it less. In other words, people judge an experience by how the event ends. Psychologists refer to this as the “peak-end rule.”
This can also explain why 2-week vacations are not necessarily remembered more fondly as 1-week ones. What seems to matter is how they end.
Similarly, negative endings can leave us with a bad impression about what had been a pleasurable experience up until then. A common example is a breakup of a relationship as we clearly recall the painful final interaction.
Common Sense Teaching ESL 