The present study investigated the instructional value of signals for learning while comparing two animations that differed solely in the presence / absence of visual signals. Signals consisted of highlighted elements and visualization of technical terms. Both animations were implemented within complex and professional hypermedia e-learning software on cell biology leading to two evaluation versions of this software. Both versions were tested during regular biology courses in 19 school classes. A subsequent post test revealed significant better learning results when students worked with the hypermedia software that embedded the signalled animation. A quite similar pattern was observed while comparing a signalled and a non-signalled animation in an isolated and therefore more restricted empirical setting (Huk et al. 2003). Impression about the animation was evaluated with the level of agreement to five statements. The results showed a reversed pattern as compared the aforementioned stu...