Fracture toughness is a crucial mechanical property of polymer materials

directly determining their load-bearing limits and service lifetimes in practical applications. As one of the most representative classical models in polymer fracture mechanics

the Lake-Thomas theory elucidates the molecular origin of toughness in rubbers and elastomers. Despite its landmark significance in polymer fracture research

this theory has not yet been systematically incorporated into the current teaching of “Polymer Physics”

making it difficult for students to understand macroscopic fracture mechanisms from the perspective of chemical bond energy and molecular structure. Teaching practice shows that after studying the stress-strain behavior of polymers

students exhibit strong curiosity about the molecular mechanism underlying the ultimate fracture. Taking the Lake-Thomas theory as the central theme

this paper systematically reviews its historical development

reconstructs its derivation logic

and explores its application and extended models in complex polymer systems such as double-network hydrogels. Through a teaching case based on rubber-tear experiments

this study demonstrates how adopting an “inventor’s perspective” in the classroom can guide students to understand the energetic essence of molecular chain rupture

thereby deepening their comprehension of polymer fracture behavior

promoting the integration of theoretical knowledge with practical application

and enhancing their analytical and innovative thinking abilities.