Tests were conducted with a fish farm system simulation in combination with other activities in order to measure its effectiveness as an aid in teaching and learning about water chemistry and eco systems. Results support the dual coding hypothesis (Paivio, 1990) that posits two kinds of connections: representational connections between verbal stimuli and verbal representations, and between visual stimuli and visual representations and referential connections between visual and verbal representations. (Mayer/Anderson 1991) Seventy-six students from three New York City private and public schools participated in the study.