I observed a teacher in training making an activity choice with her students the other day. She asked them to complete an assignment, then a student said he would prefer to do another task instead. She responded immediately by saying "okay, how many would rather do what student X just said?" Most put their hands up and she let them do the task that was not prescribed by her.
A number of issues to consider:
a. is the teacher mindful of process or afraid to assert her direction?
b. is the student avoiding responsibility or simply choosing to take responsibility in a different way?
c. is the teacher letting students override her goals for the lesson or is she anticipating choice AND setting the parameters for reasonable choice?
d. is the teacher wanting to please or accommodating different but equally valid choices?
It was my judgment in this situation that the teacher did not think through the implications of letting a student divert the task. It appeared indecisive and lacked justification.