In this article, we describe the development of two novel approaches to teaching math and science concepts to deaf children using 3D animated interactive software. One approach, Mathsigner, is non-immersive and the other, SMILE, is a virtual reality immersive environment. The content is curriculum-based, and the animated signing characters are constructed with state-of-the art technology and design. We report preliminary development findings of usability and appeal based on programme features (e.g. 2D/3D, immersiveness, interaction type, avatar and interface design) and subject features (hearing status, gender and age). Programme features of 2D/3D, immersiveness and interaction type were very much affected by subject features. Among subject features, we find significant effects of hearing status (deaf children take longer time and make more mistakes than hearing children) and gender (girls take longer than boys; girls prefer immersive environments rather than desktop presentation; girls are more interested in content than technology compared to boys). For avatar type, we found a preference for seamless, deformable characters over segmented ones. For interface comparisons, there were no subject effects, but an animated interface resulted in reduced time to task completion compared to static interfaces with and without sound and highlighting. These findings identify numerous features that affect software design and appeal and suggest that designers must be careful in their assumptions during programme development.