Screening, definition theory

This mode was added after the first implementations, in response to student feedback. Despite the research literature to the contrary (Sweller et al. 1998), students wanted the ability to view the video with associated text (theory, definitions, and transcript) alongside. The chapter mode allows users to have the video playing on one-half of the screen and text on the other (Fig. 13.2). 

FIGURE 133 Mixed-media chart. M = main screens V = video T = theory A = animations D = definitions P = problems S = transcript R = references C = credits. 

FIGURE 13.4 Video only (M = main screens, V = video, T = theory, A = animations, D = definitions, P = problems, S = transcript, R = references, C = credits). 

According to the definition, electrostatic interactions must play an important role. From the Debye-Hiickel theory, it can be concluded that in dilute systems these interactions should be long ranged, whereas in concentrated or neat systems, they are screened and therefore short ranged. However, it should be stressed that very often other interactions (e.g., due to the ions polarizability and geometry) are of the same order of magnitude and must not be neglected. 

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