Stephen has just finished writing his first poem for his poetry slam class. He will be reciting the first 10 lines during class tonight and repeats them over and over to himself as he is walking there. Stephen is using .

Rehearsal

Explanation:

Rehearsal is act of repetitively practicing art or any work  before performing it in public presence or any form of group.

The objective of such practice is to identify any potential cause of error during practice phase only and remove that so that there is no mistake during actual performance.

Since Stephen has to recite his poem in front of class. He is practicing it beforehand and hence he is indulging in rehearsal process.