In collaboration with preservice elementary teachers and in-service kindergarten teachers, the authors engaged in small-scale, demand-side production of educational software focused on numeracy skills. That is, the authors built applications designed to address children's specific learning needs as they surfaced in the classroom and were identified by the teachers. Details about the design and rationale of the software, the collaborative development process, indications about its impact on teachers' practice, and discussion about the potential of this approach to educational software production are shared. (Contains 1 table and 8 figures.)