Time passes. Interests change. Something new catches your eye. Yes, life moves on, but you never forget your first. You never forget that lecture, book, or journal article that sparked the flame that ignited your career – it’s always a part of you. For many of my colleagues in measurement and assessment it likely was Messick’s 1989 chapter on Validity, Webb’s work on alignment, or the NRC’s Knowing What Students Know that provided that spark. For members of my NEERO family, I’m guessing it was something by Vygotsky or Marilyn Cochran-Smith. For me, it was “The 2 Sigma Problem: The Search for Methods of Group Instruction as Effective as One-to-one Tutoring” by Benjamin Bloom; yes, the Benjamin Bloom of Bloom’s Taxonomy and Bloom, Hastings, and Madaus.
The article was published in Educational Researcher in the summer of 1984 as I completed the first year of my doctoral program at the University of Minnesota and was heading home to Boston to get married. Before leaving Minneapolis, I had also just accepted a research assistantship on a project evaluating an innovation in instructional technology designed to enhance interactions between a teacher and a classroom full of students. The Bloom article became our 95 Theses and Common Sense as we designed and carried out research studies to solve the 2 sigma problem in our little teched-out classroom in St. Paul.
I write about the 2 Sigma Problem today because in the past few months I have seen Bloom’s 1984 article cited a number of times in discussions of competency-based education. Invariably, those authors recount Bloom’s description of Mastery Learning with its feedback and corrective procedure as an example of an approach that could significantly enhance student achievement, getting us halfway to the 2 sigma goal (not a bad start, but as anybody who has tried to lose weight knows, that first sigma is the easiest).
Yes, it is true that Bloom had extensive experience with Mastery Learning and that it is featured prominently in the article. It’s difficult for me to imagine, however, someone reading the article and leaving with Mastery Learning as their main takeaway. I’m sorry, but that’s like going to a Taylor Swift concert and saying there was a song about her ex-boyfriend. Yes, of course there was, but there was so much more.
A major portion of the 1984 article is devoted to a discussion of the search for “the alterable variables that have had the greatest effects on school learning” and as Bloom explains “within the last 3 years, this search has been aided by the rapid growth of the meta-analysis literature” on sets of alterable variables. Think John Hattie.
Bloom argued that the goal should not be to conduct research on stable or static variables that could not be easily changed, but rather to identify the sets of alterable variables that reduced the correlation between those static variables and student achievement.
Back to The Future
A little context might enhance understanding of the significance of this discussion of alterable variables in 1984. Although we didn’t know it at the time, this was the peak of a new era of research on input and process variables. We were still early in the shift from a “teacher-centered” to “student-centered” view of teaching and instruction. And the meaning of “student-centered” in 1984 was very different than what we mean today by the term “student-centered” instruction with an emphasis on the student as an active agent in the instructional process. In 1984, the term was simply the acknowledgment that teaching was more than lecturing; that there had to be a connection between teaching and learning; that for teaching and learning to occur, teacher behaviors had to be influenced by students’ learning and behaviors.
In describing alterable variables and the revolution in educational research that was underway at the time, Bloom identifies four key factors from his 1980 work, The New Direction in Educational Research: Alterable Variables
- Movement from the study of the actors (teachers and students) to the study of teaching and learning as they take place under specific environmental conditions
- Educational research centered on the teaching and learning process that is focused on the causal links between process variables and the qualitative and quantitative changes in the learning of students which he describes as very different from the pre-post demonstration studies of an earlier period.
- Educational research guided by models and theories which embody causal links.
- The movement from stable or static variables to variables which are alterable either before the teaching-learning processes or as a part of these processes.
Bloom describes this shift in the variables used in educational research as “central in the new view of education,” enabling “researchers to move from an emphasis on prediction and classification to a concern for causality and the relations between means and ends in teaching and learning.” He discusses five examples to contrast so-called stable or static variables which are largely out of the control of a district or school and alterable variables which can be shaped to improve student learning:
- Available time vs time-on-task
- Intelligence vs Cognitive Entry (i.e., the specific knowledge, abilities, and skills that are essential prerequisites for learning a particular school subject – and make no mistake, Bloom was a strong proponent of the teaching of “higher mental processes” even within Mastery Learning.)
- Summative vs Formative Testing
- Teachers vs Teaching
- Parent Status vs Home Environment
As I stated above, we didn’t realize at the time that the mid- to late-1980s would be the peak of research on learning processes for the next three decades. Fallout from A Nation at Risk, published in 1983, began a shift away from inputs and processes and by the end of the 1990s, a mere 15 years later, educational policy (and the research it funded) had fully regressed to a focus on outcomes and pre-post studies. Fortunately, however, tides turn, pendulums swing, and the educational policy and accountability worlds seem ready to refocus their energies on processes and causal links to student learning.
A New Hope
Like many people and things that inspire, the Bloom article did not simply present research findings, but offered a challenge: find the classroom solution that approached the 2 sigma effect of one-to-one tutoring. The article was a call to action.
So, where are we today in the search for the solution to the 2 sigma problem? Earlier this month, I attended a virtual Radcliffe Institute webinar titled, Is Now the Time to Build a Better System? K-12 Education and Systemic Racism in the Era of COVID-19. In discussing student reactions to the recent spring of remote learning, one panelist told of a student who said, “I want to be able to click a button and have a teacher come to help me.” In conjunction with other aspects of student-centered and personalized instruction and learning, that sentiment is arguably the 2020 equivalent of the 2 sigma problem and one-to-one tutoring.
And perhaps the solution is not out of reach. Technology has enabled the expansion and enhancement of “call-a-teacher” programs with real teachers that some districts have had in place for decades, and companies like Cognii are making great strides in virtual tutoring systems to support students and classroom instruction. Much of the progress in this area will be a direct result of the mindset that the student is an active participant in their own instruction and learning; so that to some extent, each student is already a combined teacher/student group of one.
I feel more confident now than ever that if educational research, cognitive science, neuroscience, and perhaps even data science can just help us settle on what to teach and how to teach it we will be able to build systems to provide the benefits of one-to-one tutoring, solve the problem Bloom placed before us in 1984, and perhaps even surpass 2 sigma.
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