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What Is a Bottleneck? What Is a Threshold Concept?

A bottleneck is a place in a course where, over and over again, large numbers of students fail to learn. For example, architecture students find it difficult to create the intention and representation of an initial design concept. Bottlenecks are important because they signal where students are unable to grasp crucial ways of knowing in our fields.

A threshold concept is a kind of bottleneck that asks students to make a paradigm shift to operate in a disciplinary way—with understanding of the concept, the student is transformed. Some examples of bottlenecks that are also threshold concepts include geologic timescale, textual analysis in English, and inheritance in biology. While all threshold concepts are bottlenecks, not all bottlenecks are threshold concepts.

Some bottlenecks seem to exist outside the content of the course. Emotional bottlenecks may show up in student beliefs, such as, “I cannot write.” Another kind of emotional bottleneck is the reaction when students feel their identity is being criticized, “You are attacking my heritage…stop beating up on us.” This comment reveals a fundamental concern that may in fact be related to the underlying epistemology. Emotional bottlenecks can interfere with the cognitive task. Study methods can also be bottlenecks, a metacognitive kind. For example, over reliance on memorization can leave students unprepared to answer analytic questions.

By focusing our teaching on bottlenecks and threshold concepts, we can lead students into the ways of knowing in our fields. 


Meyer, Jan and Land, Ray, eds. (2006). Overcoming Barriers to Student Understanding: Threshold concepts and troublesome knowledge. London: Routledge.

Middendorf, J.K., Mickute, J., Saunders, T.H, Najar, J.D. (submitted). What’s feeling got to do with it? Decoding emotional bottlenecks in the history classroom. Teaching History

Shopkow, L., Diaz, A., Middendorf, J., & Pace, D. (2013). The History Learning Project “Decodes” a Discipline:  The Marriage of Research and Teaching. In Kathleen McKinney (ed.) SoTL in and Across the Disciplines. Bloomington, IN: Indiana University Press. 

Who Is Doing This at IUB?

More than 100 professors have participated in the Freshman Learning Project and the History Learning Project. Faculty learning communities use the Decoding the Disciplines methodology so that numerous instructors, including Jen Shang, across campus are “decoding” the bottlenecks in their classes.

For More Help or Information

For more about bottlenecks, threshold concepts, and Decoding the Disciplines methodology, contact Joan Middendorf or another instructional consultant at the CITL.