Biological Variation as a Threshold Concept: Can We Measure Threshold Crossing?

Area of Science:

• Biology Education
• Evolutionary Biology
• Concept Learning

Background:

• Threshold concepts are crucial for discipline mastery, transforming student perception.
• Limited empirical evidence exists for threshold crossing and mastery in learning.
• Biological variation within species is a key threshold concept for understanding evolution.

Purpose of the Study:

• To examine student understanding of biological variation using four dimensions of a threshold concept.
• To measure "threshold crossing" in students learning about variation.
• To investigate the utility of the threshold concept framework for curriculum design.

Main Methods:

• Semistructured interviews were conducted with 29 students in a variation-enriched curriculum.
• A cross-sectional design included precurriculum, current, and postcurriculum groups, plus an advanced outgroup.
• Analysis focused on four dimensions: discursive, troublesome, liminal, and integrative.

Main Results:

• Students in current and postcurriculum groups showed expanded variation discourse and more integrative responses.
• Discomfort and uncertainty (liminality) were observed across groups, regardless of accuracy.
• Patterns indicative of threshold crossing emerged when analyzing all four threshold concept dimensions.

Conclusions:

• The study provides empirical evidence of threshold crossing related to biological variation.
• Findings offer insights into curriculum design for effectively teaching threshold concepts.
• The threshold concept framework is valuable for analyzing and improving science education.