Throughout the chapter, we have characterized professional development activities in terms of structural and core features. To test this view of professional development, we estimated a formal causal model, using data from our national sample of teachers. Since it is possible that teachers in different types of schools or teachers with different characteristics may experience different types of professional development, we have included school and teacher characteristics as control variables in our model. The results are shown in Exhibit 3.21 . The results shown are expressed as standardized path coefficients, which represent the relative influence of one variable on another.
All paths shown are statistically significant.
34 Time span and amount of time have a substantial positive influence on opportunities for active learning and coherence. The fact that both time span and contact hours have independent effects on our measures of core features suggests that both dimensions of duration are important. Professional development is likely to be of higher quality if it is both sustained over time and involves a substantial number of hours. As we anticipated, all three of our measures of the core features of activities have a positive influence on enhanced knowledge and skill, as reported by the teachers in our sample. Both content focus and coherence have substantial positive effects on enhanced knowledge and skills, indicating that activities that give greater emphasis to content and that are better connected to teachers other professional development experiences and other reform efforts are more likely to produce enhanced knowledge and skills.