The ever increasing use of "service learning" as an adjunct to the ongoing instructional programs in public schools and higher education has challenged the conduct of both formal and informal evaluations. This article considers threats to internal validity in evaluating "learn and serve" projects with particular attention to data collection design and instrumentation. Mixedmethods designs are likely to be most effective, particularly when the intent is to focus on valueadded assessment, and there is considerable variability in the nature and extent of implementation of learn and serve activities.
Payne, David A., "Methodological Problems in Evaluating Service Learning Projects" (1997). Evaluation/Reflection. 50.