There are, however, several open research issues with regard to using these hybrid
animations. One issue is that it is necessary to identify the components that added to the
effectiveness of the hybrid animations as they showed two types of information. The first
was the transitions between representations. The second was, in the animations of the
solution procedure, an explicit mapping between the elements of the abstract animations
and the mathematical expressions mentioned in the worked examples was established by
displaying connecting lines between the two (not shown in Fig. 1). Thus, further research
needs to disentangle the effects of morphing versus the effects of explicit mapping as the
latter has been shown to be effective when learning from text-picture combinations by
itself (e.g., Huk and Steinke 2007; Narayanan and Hegarty 2002).