What data collection instruments will be the most appropriate to address this topic? Why?

Generating and collecting qualitative data

Description

Suppose you are interested in the behaviors of college professors that have high ratings of student satisfaction.

The research goal is to identify the teaching behaviors of these successful professors so that these behaviors can be built into the curricula of doctoral leadership programs.

The sample for this study will consist of 10 randomly selected professors who received high end-of-course survey scores.

You want to use a case study design that requires at least two sources of data.

What data collection instruments will be the most appropriate to address this topic? Why?