Most American schools are organized following some version of the egg crate model, with teachers tending to work in isolation and without structures to support collaborative improvement.12 Research on the impacts of working more collaboratively tend to be studies of variations on that essential egg crate model rather than studies of schools organized in wholly collaborative ways. This may be because most instances of establishing or improving collaboration are themselves modifications rather than holistic reforms. As noted by Katrien Vangrieken and colleagues, “It is more difficult to change the whole school culture and structure than it is to create interventions for teachers and groups of teachers.”13
Bearing in mind the realities of reform and the limitations of the research, studies have been undertaken using various types of data focused on school-level collaboration. This research has shown that schools in which teacher collaboration is encouraged tend to have higher student achievement than less collaborative schools. These studies typically use standardized test scores to measure achievement. They assess how collaborative schools are in various ways, including analyzing schools or districts that have made specific efforts to encourage collaboration or using surveys that ask teachers how collaborative their schools are.
Analysis of nearly a decade of data from schools in an urban North Carolina district, one of the largest in the country, showed that teachers achieved greater increases in their students’ standardized test scores in schools with supportive professional environments—especially those with more peer collaboration and a positive school culture—than did teachers in schools with less supportive professional environments.14 Other research analyzing two years of data on more than 9,000 teachers in 336 Miami-Dade County public schools showed that schools with better-quality collaboration—meaning teachers reported that their collaboration in instructional teams was both “extensive” and “helpful”—had higher student achievement gains in math and reading.15 This held true even controlling for other characteristics of those schools’ students and teachers, meaning the researchers could be more confident that the difference was related to the quality of collaboration at the school and not to differences in the students and teachers themselves.16
Further evidence of how a collaborative teacher workplace can improve student achievement comes from the extensive longitudinal research by the University of Chicago Consortium on School Research, led by Anthony Bryk, in hundreds of Chicago elementary schools. This team developed a model of essential school supports in order to better understand why some schools improve outcomes for students whereas other schools do not. One of these essential supports is a school’s “professional capacity,” which includes several elements: the quality of its human resources, the quality of its professional development, norms of continuous improvement and “professional community.” Professional community, as Bryk and colleagues explain it, refers to a new arrangement for teachers, one dependent on collaboration. It makes their work public to their colleagues, requires critical questions and relies on a normative commitment to student improvement.17 (For more on this topic, see the subsection on professional communities.)
Bryk and colleagues’ research provides insight into how the different elements of professional capacity and other essential supports interact in ways that impact student achievement. For instance, Bryk and colleagues found that schools in their study characterized by a strong professional community were about four times as likely to see a substantial improvement in students’ reading and math scores than schools that had a weak professional community.18 Further, they found that even more schools had gains in reading and math where a strong professional community was paired with other elements of other essential supports, such as an aligned curriculum: Between half and two-thirds of schools with a strong professional community and an aligned curriculum saw substantial improvements in student reading scores, and 40 percent saw substantial improvements in math scores.19 Not a single school in their study that reported weakness in those two areas saw improvements in either reading or math.20
These studies confirm similar conclusions from earlier case studies. For example, a case study of elementary schools in a large Midwestern school district found that schools with higher levels of teacher collaboration “for school improvement” were associated with higher student achievement on math and reading tests. This held true even when controlling for student demographics, school size, proportion of low-income and minority students and other factors.21 Teachers whose student teaching took place in more collaborative schools have actually been shown to raise student achievement in math more when leading their own classrooms than teachers who student-taught in less collaborative schools.22
Much of the research discussed above focuses on understanding schools that are already characterized by collaboration or in which teachers already have strong social connections and comparing them with less collaborative environments. However, research on specific approaches to fostering collaboration has found them to have different degrees of effectiveness in improving student achievement.
The approaches to collaboration described below are not the only ways in which teachers work together, and some of these approaches have attracted more attention than others from researchers. For more detail on these and other approaches to fostering collaboration, see the section on how teachers collaborate.
One specific approach to fostering collaboration is teacher-to-teacher mentoring. (For more on this topic, see the subsection on mentoring.) Evidence is mixed for the effectiveness of mentoring on improving student achievement. Two large randomized controlled studies found contradictory results. An on-the-job peer mentoring intervention in 16 schools in a low-income Tennessee school district found that student achievement improved under mentored teachers and across the schools overall where mentoring took place.23 Yet a study of two comprehensive mentoring programs used in a random set of 418 elementary schools across 17 urban school districts found no difference in student achievement after one or two years of the mentorship programs, although it did find a small increase in student achievement in reading and math after three years, only if the teacher participated in the program for two full years.24
Another approach to fostering collaboration is professional communities or professional learning communities (PLCs). (For more on this topic, see the subsection on professional communities.) Professional communities or PLCs vary in a number of ways, such as how rigorously they are implemented, the contexts in which they are implemented and who joins them. These variations may lead to differences in PLCs’ effectiveness. A review of 11 studies of schools that used PLCs concluded that achievement improved when teachers in PLCs shared an explicit goal of focusing on student learning.25 It also concluded that the percentage of students performing at grade level often increased after schools adopted PLCs and that the percentage of students performing at grade level was often higher in schools that adopted PLCs than in schools that did not.26 That review highlighted the need for PLCs to be “well developed” in order for them to have positive impacts on teaching practice and student achievement.
Finally, creating shared leadership among principals and teachers is another specific approach to fostering collaboration. (For more on this topic, see the section on principals.) Principals can play key roles in fostering teacher collaboration that improves student learning and achievement. For example, a randomized controlled trial of a program in rural Midwestern elementary schools showed a strong association between increasing shared instructional leadership between principals and teachers and increased collaboration among teachers themselves. That increased teacher collaboration was in turn associated with increases in students’ math and reading achievement.27
Under the traditional egg crate model of teaching, a teacher’s effectiveness would be attributed solely to his or her independently held knowledge and skill. But some studies suggest that teaching effectiveness can depend on teachers’ opportunities to learn by working together and sharing ideas. These studies highlight the importance of how teachers might work together to solve problems that occur in their classes but that also likely extend beyond any individual classroom. They additionally highlight the importance of building trust among teachers across departments and of structuring opportunities for teachers to establish a shared vision for their school and students.
Based on further analysis of their 2009 research across a representative sample of 130 urban public schools with more than 1,000 fourth- and fifth-grade teachers who were using the same math curriculum in their classrooms, researchers Carrie R. Leana and Frits K. Pil published findings on the Shanker Institute blog in 2014. They found that these teachers’ “social capital”—which the researchers defined as the resources and skills teachers could access through social connections with other teachers—was more strongly related to student achievement than these teachers’ “human capital”—which the researchers defined as teachers’ formal education, grade-level experience and ability to interpret students’ mathematical thinking. Students of teachers identified as having high social capital but lower human capital performed as well as students of teachers with average human capital and average social capital.28
An earlier study by the same researchers also found promising results when examining the relationship between social capital and student achievement. That study of 88 schools (including elementary, middle and high schools) across a low-income, urban district included a focus on the level of “internal social capital”—in this study, a composite score based on teachers’ self-reported sense of the level of trust, information sharing and shared vision within their school. The study explored the relationship between internal social capital and student achievement. It found that higher levels of internal social capital were a predictor of improvement of student achievement on test scores in both reading and math and that higher levels of internal social capital were a predictor of higher instructional quality, even when taking student socioeconomic status and other factors into account. The researchers also found a significant relationship between teachers’ human capital, which in this study they measured using years of teaching experience in the subject matter, and students’ reading achievement, but they did not find a significant relationship between teachers’ human capital and students’ math achievement. They concluded that their findings suggested “little support for the human capital explanations of school performance.”29 Overall, measures of schools’ internal social capital explained more of students’ performance gains than measures of teachers’ human capital.30
Collaboration among teachers in interpreting and using student test score data might make such data more useful and therefore advance school improvement efforts. The focus on teacher use of assessment data to improve instruction has increased in the context of state standards and student testing, yet efforts to facilitate the use of that data have largely focused on teachers as individuals. For instance, an explanatory study documenting district-mandated use of data by math teachers in nine elementary schools across two districts in Pennsylvania concluded that the structures in place to provide individual teachers with analyses of their students' scores on interim assessments were not sufficient on their own to facilitate teacher understanding of interim assessment data in order to lead to changes in instruction.31
However, some researchers—such as Judith Warren Little in her 2012 review of the literature—have pointed out that studies on data use have failed to focus on how teachers collaborate around data and how that relates to teachers’ understanding and use of data.32 A 2012 review by Alan J. Daly showed that many studies have found positive results related to collaborative data use in various contexts and at various educational levels.33 One such study looked at data use by teachers in five low-income urban high schools and found that collaboration among teachers was important to improvement. It improved teachers’ capacity to understand data, helped them maintain a focus on student achievement, and facilitated learning across administrators, guidance counselors and teachers, providing context for the instructional improvements.34
That study and others make clear that collaboration alone is not a sufficient condition for improving data use for instructional improvement. While collaboration is seen as an important component of such efforts, other important components include having user-friendly data systems in place35 as well as leadership that supports work routines around data interpretation and even ongoing data literacy development.36
There has been an increased focus on funding more comprehensive studies on data use.37 However, some researchers have cautioned about the overemphasis on data use in collaborative settings, arguing that instruction should be data informed but driven by professional judgment that is able to interpret data in context and make decisions responsive to the needs of students.38