Impact of the Understanding Science Professional Development Model on Science Achievement of English Language Learner Students
Study design
This study, an experimental trial, runs from spring 2009 to spring 2010, serving six regions in California and one urban district in Arizona. This study's unit of assignment is the teacher. At each of the six research sites, around 20 volunteer teachers participate in the study. Treatment group teachers take an Understanding Science course in August 2009, incorporating what they learn there into their instruction of force and motion in the subsequent fall semester. Control group teachers participate in their regular professional development activities and continue using their usual instructional practices in the fall.
Approximately 120 volunteer teachers are randomly assigned to treatment and control groups. Where two or more teachers in a school agree to participate, teachers are randomly assigned to treatment and control groups within the school. Where only one teacher in a school is participating, likely the more common case, researchers will randomly assign schools to treatment and control groups.
With 120 teachers and an average of 40 students served by each teacher, the study is powered to detect program impacts of 0.17–0.20 standard deviation units on academic outcomes for general and English language learner students, which is equivalent to about two-thirds of a year of growth by middle school students on norm-referenced standardized tests in reading (Hill et al. 2008). And for teacher outcomes, the projected sample size is sufficient to detect impacts greater than 0.46 standard deviation units. Impacts of this magnitude would be expected at the more proximal teacher level to produce smaller subsequent impacts at the more distal student level.
One limitation of the study is the short period of implementation. Impact estimates will be based on a sample of treatment teachers who are using what they have learned from the professional development for the first time. These teachers will not have the benefit of having practiced the instructional approach in prior semesters. Another limitation is the inadequate sample size for examining differential impacts on student subgroups. Differences in program impacts for student subgroups, particularly for English language learner and English-proficient students, can only be examined in an exploratory manner. But the main effects of the intervention on the performance of all students and for English language learner students can still be examined.