As subject knowledge becomes increasingly complex—with accumulating facts and an expanding web of connections—students often struggle to make sense of these non-linear and multidisciplinary relationships. Research shows that they face challenges in integrating facts into a coherent framework and applying this understanding across different contexts (Martin‐Piedra et al., 2023). Teachers play a crucial role in guiding students to discern patterns and derive meaning from these connections. But how do they achieve this?

Meyer and Land (2003) described such conceptual “bottlenecks” as threshold concepts—ideas that are transformative, integrative, liminal, and irreversible. These fundamental disciplinary concepts mark a shift from a familiar perspective to a previously inaccessible way of thinking. Numerous studies have explored threshold concepts across disciplines, such as physics (Bhatia et al., 2022), biology (Dunn, 2019), and literary studies (Corrigan, 2019). Typically, researchers identify threshold concepts by examining whether they exhibit these four characteristics, with teachers playing a key role in recognising them. However, research rarely delves deeper into the underlying nature of these concepts.

We propose moving beyond this descriptive approach to investigate the structural foundations of threshold concepts. Specifically, we argue that threshold concepts are rooted in natural language and share key features of conceptual metaphors, as described in cognitive linguistics (Lakoff, 1980). These concepts shape diverse ways of thinking, identification, integration, and imagination (Fauconnier & Turner, 2002; Kövecses, 2020). We hypothesise that threshold concepts are underpinned by conceptual metaphors deeply embedded in the history of disciplinary discourse—including its outdated models and erroneous deviations. Consequently, threshold concepts operate within two interwoven dimensions: the body of disciplinary knowledge (including its historical development) and the learner’s individual cognitive effort.

By situating threshold concepts within the realm of thinking, we reframe their role in education. Rather than identifying a fixed set of concepts deemed crucial by experts (e.g., the atom in natural sciences (Bhatia et al., 2022)), we explore whether teachers, even implicitly, associate students’ learning difficulties with their efforts to decode complex, multi-layered metaphorical models.

Previous research has explored teachers’ perceptions of threshold concepts in the natural sciences (Zepke, 2013; Park, 2015). Our study shifts the focus to the humanities—specifically, literary studies—a structurally more fluid domain that is permeated by metaphorical thinking at every level. We hypothesise that this metaphorical exposure will allow us to trace the nature of threshold concepts more effectively.

Readers of literary texts engage with two dimensions: their own interpretation and the author's intended meaning (Lotman, 2018). Their understanding is inherently uncertain and subjective, making the teacher’s role in guiding students through subtle patterns and connections even more critical.

Our research questions are as follows:

1. Do literature teachers explicitly support students’ thinking and, in particular, acknowledge their encounters with threshold concepts in literary texts?

2. Does teachers' approach to introducing complex disciplinary content reflect an awareness of threshold concepts?

3. What strategies do teachers use to address threshold concepts: do they primarily rely on their own learning experiences, or do they facilitate students’ independent discovery?

To test our hypothesis about the metaphorical nature of threshold concepts and answer our research questions, we will analyse best teaching practices as demonstrated in concept-based, multidisciplinary lesson plans focused on national literature. Our sample consists of 72 lesson plans created by teachers of national language and literature who participated in the 2023 Teacher Learning Design Competition in Russia. This competition attracts experienced and proactive educators, ensuring that our dataset reflects exemplary teaching practices. Each teacher was tasked with designing a lesson (or a series of lessons) based on the same set of literary works: two poems and one short story exploring the theme of architecture’s influence on people. The lesson plans included detailed instructional designs along with additional questions and exploration prompts for students. To further contextualise these lesson plans, we will conduct semi-structured interviews with the teachers (n = 72) to examine their own experiences with threshold concepts. According to our hypothesis, threshold concepts function as multi-layered, implicit, and often fossilised conceptual metaphors. Originally conceived as comparisons, these metaphors have since evolved to signify broad conceptual directions rather than direct analogies. This allows us to reconstruct each teacher’s conceptual domain and analyse their cognitive approach to the literary texts in question. Through frequency analysis and conceptual field modelling (Lakoff, 1973), we will examine how individual teachers construct knowledge about texts and whether they explicitly or implicitly engage with complex conceptual metaphors as part of overcoming threshold concepts. Our preliminary analysis has identified four clusters of teachers’ approaches: Teachers who explicitly recognise and address threshold concepts, drawing on their own experiences in overcoming them. Teachers who acknowledge threshold concepts but lack sustained experience in addressing them. Teachers who do not explicitly emphasise threshold concepts but still employ teaching methods that facilitate engagement with them. Teachers who are unaware of threshold concepts and whose approaches do not account for them.

We aim to determine whether teachers—consciously or unconsciously—incorporate implicit metaphorical mechanisms in their teaching strategies. If so, this would suggest that working with threshold concepts is already embedded in their instructional approaches, even if not explicitly recognised as such. Additionally, our findings will contribute to a better understanding of the systemic behaviour of threshold concepts and their role within educational and cognitive frameworks. By identifying effective teaching strategies that promote conceptual understanding, we hope to outline a structured approach to addressing learning difficulties—one that can be extended beyond literary studies to other disciplines.

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