The purpose of the study was to develop mathematical instructional card game titled "algebrameter" and determine its efficacy in remediating junior secondary school (JSS) students' learning difficulties in algebra and geometry. The study employed research and development design. A sample of 120 JSS II students drawn from a population of 4800 JSS II students in Nsukka Education Zone, using multi-stage sampling procedure participated in the study. Algebra and geometry achievement test (AGAT) comprised 30 multiple choice questions developed by the researchers was used for data collection. The internal consistence of AGAT was determined using Kuder-Richardson formula 20 (KR-20) formula, which yielded a value of 0.82. Research questions were answered using mean and standard deviation while the hypothesis was tested using analysis of covariance. The results of this study revealed that students who were exposed to "algebrameter" significantly performed better than students who were not exposed to "algebrameter" package.