Introduces the articles of this theme issue, which aim to clarify the conditions under which multiple forms of representation are likely to support comprehension in multimedia learning environments and how specific features of multimedia can help learners learn complex subject matter. (SLD)

Comments on the papers of this theme issue, which are concerned with the impact of verbal and nonverbal representations in acquiring expertise in complex domains. Outlines lessons from first generation work in this field and issues for second generation research. (SLD)

Identifies and summarizes instructional messages in the articles in this theme issue and also identifies central theoretical issues, focusing on: (1) external representations; (2) dual coding theory; and (3) the effects of animations on learning. (SLD)

Introduces six articles on the instructional implications of cognitive load theory (CLT). CLT is based on a cognitive architecture that consists of a limited working memory, with partly independent processing units for visual and audio information, which interacts with an unlimited long-term memory. (SLD)

Comments on recent trends in cognitive load theory discussed in the papers in this special issue. Considers the external management of cognitive load through means of optimal instruction and the internal management of cognitive load by learners' metacognitive and self-regulative competence. (SLD)

This introduction to the special issue shows how it brings together and integrates the most recent theoretical, empirical and practical developments in the field of interest and learning. (SLD)

Comments on the articles of this special issue, which highlight significant changes in instructional design based on the theory of conceptual change. Evidence from these studies suggests the interplay of evolutionary and revolutionary aspects of conceptual change that are content and context dependent. (SLD)