I agree with Doug--you will notice right away if something is not working correctly, so a large sample size is not that important. Formative evaluation is an iterative process. Test until you reach what you have set as the goal for that component. And if it's too complicated, break it down and test those subcomponents using the same iterative process. I enjoy formative evaluation b/c it is so quick (when compared to other types of evaluation) and gratifying b/c you see immediate results--unfortunately, not always positive ones! Wendy Calvert Consultant [log in to unmask]