Does speed provide a "model for" rate of change in other contexts? Does JavaMathWorlds (JMW), animated simulation software, assist in the development of the "model for" rate of change? This project investigates the transference of understandings of rate gained in a motion context to a non-motion context. Students were 27 14-15 year old students at an Australian secondary school. The instructional sequence, utilising JMW, provided rich learning experiences of rate of change in the context of a moving elevator. This context connects to students' prior knowledge. The data taken from pre- and post-tests and student interviews revealed a wide variation in students' understanding of rate of change. The variation was mapped on a hypothetical learning trajectory and interpreted in the terms of the "emergent models" theory (Gravemeijer, Math Think Learn 1(2):155-177, 1999) and illustrated by specific examples from the data. The results demonstrate that most students were able to use the "model of" rate of change developed in a vertical motion context as a "model for" rate of change in a horizontal motion context. A smaller majority of students were able to use their, often incomplete, "model of" rate of change as a "model for" reasoning about rate of change in a non-motion context.