Editorial

How to define and measure teaching quality is a question that has been raised for many years already. Numerous studies have outlined the complexities of the teaching quality concept, and the strengths and limitations of the various options for measuring it. These measurement options range from qualitative self-reports by teachers themselves to quantitative, value-added measures of how much students learn in teachers’ classrooms. In the well-known Measures of Effective Teaching (MET) project (Kane, McCaffrey, Miller, & Staiger, 2013), three measures were combined for answering the question whether effective teachers can be identified: value-added measures of teacher output, classroom observations of lesson quality by expert observers, and students’ perceptions of teaching quality. Although the conclusion of the MET project was that effective teachers can be identified by means of these three measures, still many issues remain.

For that reason, an international workshop was organized by the editors of this special issue at the University of Twente in The Netherlands. In the workshop, experts from Germany, Norway, England, the USA, and The Netherlands addressed various issues of measuring and improving teaching quality. Based on the workshop presentations and discussions, the articles of this special issue were written.

In the first article, Bell, Dobbelaer, Klette, and Visscher first explain what a classroom observation system for measuring teaching quality encompasses, and next they present a framework for analyzing (the differences between) observation systems. Observation systems can differ, for example, in the teaching dimensions they focus on, in the scoring procedures used, and also in the available empirical evidence for their content. The framework is used by the authors for identifying the differences between four well-known classroom observation systems: the Protocol for Language Arts Teaching Observation (PLATO), the Trends in International Mathematics and Science Study (TIMSS), the International Comparative Analysis of Learning and Teaching (ICALT), and the Classroom Assessment Scoring System (CLASS).

In the second article, by Van der Scheer, Bijlsma, and Glas, the focus is on the validity and reliability of student perceptions of teaching quality in primary education. When it comes to student perceptions, an important concern is that students are not able to differentiate between different teaching quality constructs (e.g., classroom management skills and instruction skills). This raises questions regarding the value of student perceptions. In the article, however, evidence is provided for the discriminant validity of student perceptions and also for the relationship between student perceptions and classroom observations conducted by external raters. The findings of the study indicate that student perceptions can provide valuable information about teaching quality.

Although differentiation is a very popular topic in education, it is not always clear what precisely is meant by it and what “quality differentiation” looks like. Van Geel, Keuning, Frèrejean, Dolmans, Van Merriënboer, and Visscher in the third article start with presenting the results of a cognitive task analysis of the characteristics of quality differentiation. On the basis of their findings, they thereafter question whether the instruments used for measuring differentiation in classrooms really capture the full complexity of differentiation.

Given the complexity and multidimensional nature of teaching, it is not surprising that many different approaches to evaluating teaching quality exist. Building on the other three papers of the special issue, the final article by Gitomer provides a framework for considering the evaluation of teaching quality. The value of such a framework is that it can situate particular evaluation approaches within a larger context, and provide a way to understand the commonalities and distinctions between different approaches in terms of what teaching constructs are measured and how they are measured. Gitomer also reflects on each of the three individual articles of the special issue and concludes that each article contributes to a more nuanced and thorough understanding of the complex teaching quality construct, on which future research can build.