Active student responding (ASR) has been shown to be an effective way to improve the mathematical skills of students. One specific method of ASR is the use of response cards. In this study, a system of least prompts combined with response cards was used to increase mathematical knowledge, and number identification, of three elementary students with significant disabilities (age range, 7-10 years, IQ range, greater than 20-44) via a multiple probe design across participants. A functional relationship was demonstrated between student responding (increased number identification) and the implementation of the least to most prompting system. Maintenance checks, after the intervention was concluded, demonstrated that the skill level was sustained. Limitations and future research are discussed. (Contains 1 table and 1 figure.)