The coach could grade their performance.
Social loafing refers to the fact that a person might not produce much effort when in a group, as opposed when alone. So, these kids know that together they are pretty good, so they don't have to try hard; but when they are alone, they do. In order to prevent this, the coach might want to grade their performance, because then they will try harder.
Jeremy's behavior is under pretty tight stimulus control.
Stimulus control refers to the fact that an individual will behave one way when presented with a particular stimulus, and behave completely differently when that stimulus is absent. In Jeremy's case, he avoids any interaction with that German shepherd, but he is not afraid of dogs in general.
