Testimonials from volunteers, staff, and beneficiaries of an organization can go a long way in demonstrating the impact of a program, if they are collected in the right way.
For example, the specificity of the questions you ask plays a critical role in the quality of the response.
Nancy Schwartz provides some hints on how to get quotes that best capture your programs and their impact in Seven Steps to Compelling Testimonials for Nonprofit Organizations. It’s definitely worth a look, especially if you include testimonials as part of your backup documentation for a grant request (which I recommend in most cases) or your program collects comments from parents or other beneficiaries as part of an end-of-year assessment.