Abstract: Animated diagrams representing dynamic systems hold great potential for improving the way people learn. However, so far the literature failed to find clear benefits of animated diagrams. Consequently it is worthwhile to investigate conditions under which enhancement of learning occurs. In the present study interactivity of the display and spatial ability of learners were examined. Three modes of presentation were compared: static diagrams, animation with interactivity, and animation with focus, also combined with interactivity. The interactive animation condition with focus acquired more knowledge than the other two conditions while the interactive animation condition scored worst. High-spatial ability subjects performed better on the knowledge acquisition measures than low-ability subjects. The interactive animation condition with focus is particularly beneficial for lowspatial ability subjects. These results indicate that combining the conditions of interactivity and focus does lead to improvement in learning from animations, particularly for low-spatial ability subjects.