Our research objective focused on monitoring students´ mental effort and cognitive achievement to unveil potential effects of an instructional change in an out-of-school lab offering gene technology modules. Altogether, 231 12th graders attended our day-long hands-on module. Within a quasi-experimental design, a treatment group followed the newly developed two-step approach derived from cognitive load theory while a control group applied experimentation in a conventional one-step mode. The difference consisted of additional focused discussions combined with noting students´ ideas (step one) prior to starting any experimental procedure (step two). We monitored mental effort (nine times during the teaching unit) and cognitive achievement (in a pre-post-design with follow-up test). The treatment demonstrated a change in instructional efficiency (by combining mental effort and cognitive achievement data), especially for intrinsically high-loaded students. Conclusions for optimizing individual cognitive load in science teaching were drawn.

https://www.tandfonline.com/doi/abs/10.1080/09500690902948862