We received a question from a principal of a high-performing middle school who wrote: "Although we have made significant growth in many of the core components of a professional learning community we continue to struggle with the perception of teacher autonomy as a result of attempting to create common assessments. A number of teachers continue to believe that common assessments restricts their ability to differentiate instruction from their colleagues.... our staff still remains hesitant to fully engage in meaningful collaboration which would result in creating common assessments and sharing instructional practices."

We have offered our own arguments as to why assessments created by a team of teachers are superior to the formal assessments developed by a teacher working in isolation.

1. Team-developed common assessments are more efficient.

If five teachers teaching the same course or grade level are responsible for ensuring all students acquire the same knowledge and skills, it make sense those teachers would work together to determine the best methods to assess student learning. A team of teachers could divide responsibilities for creating a unit and developing assessments. Teachers working in isolation replicate and duplicate effort. They work hard, but they do not work smart.

2. Team-developed common assessments are more equitable.

The use of common assessments increases the likelihood that students will have access to the same curriculum, acquire the same essential knowledge and skills, take assessments of the same rigor, and have their work judged according to the same criteria. We have witnessed repeated examples of teachers who were emphatic about the need for consistency, equity, and fairness in terms of how they were dealt with as adults, being completely unconcerned about the inconsistency, inequity, and lack of fairness that characterized the assessment of student learning in their school. If every teacher has license to assess whatever and however he or she determines, according to criteria unique to and often known only by that teacher, schools will never be institutions that truly model a commitment to equity.

3. Team-developed common formative assessments are more effective in monitoring and improving student learning.

We have cited several researchers who have concluded that team-developed common formative assessments are one of the most powerful strategies available to educators for improving student achievement. We know of no research concluding the formal assessments created by individual teachers working in isolation advance student learning.

4. Team-developed common formative assessments can inform and improve the practice of both individual teachers and teams of teachers.

Teachers do not suffer from a lack of data. Virtually every time a teacher gives an assessment of any kind, the teacher is able to generate data - mean, mode, median, standard deviation, percentage failing, percentage passing, and so on. As Robert Waterman (1987) advised, however, data alone do not inform practice. Data cannot help educators identify the strengths and weaknesses of their strategies. Data inform only when they are presented in context, which almost always requires a basis of comparison.

Most educators can teach an entire career and not know if they teach a particular concept more or less effectively than the teacher next door because the assessments they generate for their isolated classrooms never provide them with a basis of comparison. Most educators can assess their students year after year, get consistently low results in a particular area, and not be certain if those results reflect his or her teaching strategies, a weakness in the curriculum, a failure on the part of teachers in earlier grades to ensure students develop a prerequisite skill, or any other cause. In short, most educators operate within the confines of data, which means they operate in the dark. But in a PLC, collaborative teams create a series of common assessments, and therefore every teacher receives ongoing feedback regarding the proficiency of his or her students, in achieving a standard the team has agreed is essential, on an assessment the team has agreed represents a valid way to assesses what members intend for all students to learn, in comparison to other students attempting to achieve the same standard. That basis of comparison transforms data into information.

Furthermore, as Richard Elmore (2006) wrote, "teachers have to feel that there is some compelling reason for them to practice differently, with the best direct evidence being that students learn better" (p. 38). When teachers are presented with clear evidence their students are not becoming proficient in skills they agreed were essential, as measured on an assessment they helped to create, and that similar students taught by their colleagues have demonstrated proficiency on the same assessment, they are open to exploring new practices. When the performance of their students consistently prevents their team from achieving its goals, they are typically willing to address the problem. In fact, we consider team-developed common formative assessments one of the most powerful motivators for stimulating teachers to consider changes in their practice.

5. Team-developed common formative assessments can build the capacity of the team to achieve at higher levels.

As Wiliam and Thompson (2007) found, the conversations surrounding the creation of common formative assessments are a powerful tool for professional development. When schools ensure every teacher has been engaged in a process to clarify what students are to learn and how their learning will be assessed, they promote the clarity essential to effective teaching. When teachers have access to each other’s ideas, methods, and materials they can expand their repertoire of skills. When a team discovers the current curriculum and their existing instructional strategies are ineffective in helping students acquire essential skills, its members are able to pursue the most powerful professional development because it is specific, job-embedded and relevant to the context of their content, their strategies, their team, and their students.

6. Team-developed common formative assessments are essential to systematic interventions when students do not learn.

We argue that if educators were truly committed to high levels of learning for all students, they would not leave the question, "what happens when some students do learn" to chance. They would instead, work together to create systems of intervention to ensure any student who struggles receives additional time and support for learning in a timely and directive way. Team-developed common formative assessments are a critical element of that system of intervention.

Not every assessment should be a common assessment. There is still a place for individual teachers to create their own formal assessments. Team-developed common assessments will never eliminate the need for individual teachers to monitor student learning each day through a wide variety of strategies that check for understanding. But if schools are ever to take full advantage of the power of assessment to impact student learning in a positive way, they must include common formative assessments in their arsenal. Professional learning communities will make team-developed common formative assessments a cornerstone of their work.

Rick DuFour, Becky DuFour, Bob Eaker