Engineering Cognitive Intervention: Leveraging “Productive Failure” in pH Process Control to Catalyze Conceptual Change and Development of Pedagogical Content Knowledge (PCK)

Abstract

In the teaching of chemistry and chemical engineering experiments, operational deviations in the process control dimension are often regarded as procedural failures that urgently need to be minimized or eliminated in traditional teaching. This study challenges the epistemological assumption of avoiding errors and explores how chemistry teacher trainees can achieve core concept transformation and construct subject specific teaching knowledge (PCK) in carefully designed pH regulated "trial and error" scenarios. This study applied the theoretical frameworks of "Productive Failure" and "Cognitive Engineering" to design a "Strategic Cognitive Conflict" intervention plan using the refining of crude copper sulfate pentahydrate - a classic chemical separation unit that requires selective precipitation of Fe (OH)₃ within an extremely narrow process window (pH 3.5-4.0) - as the experimental framework. 90 chemistry teacher education students were randomly divided into an experimental group (actively encountering predetermined cognitive conflicts by limiting initial pH physical measurements and supplemented with structured diagnostic reasoning) and a control group (following the traditional "nanny style" error avoidance operating procedures). The quantitative results confirmed that although the two groups achieved statistical equivalence in the final product purity (p = 0.862, indicating that the macroscopic engineering output was not compromised by intervention), the experimental group showed overwhelming advantages in understanding the competitive dissolution equilibrium mechanism (p < 0.01, Cohen's d = 2.65), the underlying principles of precise pH process control (p <0.01, Cohen's d = 3.01), and the ability to transfer knowledge to unknown acid-base engineering systems (p < 0.01, Cohen's d = 2.93). Qualitative analysis revealed three hierarchical paths of cognitive repair: surface instrument calibration, deep equilibrium reasoning, and systemic integration. Research has shown that strategic process parameter tuning is not a system engineering disaster, but rather a core cognitive catalyst that triggers a deep conceptual shift; Through appropriate cognitive scaffolding guidance, such "failure" experiences can effectively incubate the essential system diagnostic abilities of future educators in complex engineering management and inquiry based teaching.