Using concrete and pictorial images in mathematics instruction is a research-proven strategy for many learners including students with disabilities. This strategy is commonly known as the Concrete-Representational-Abstract (CRA) Instructional Approach. This three sequence framework ultimately helps students make a connection between the concrete stage and abstract stage to achieve mastery of each mathematical concept. The National Library of Virtual Manipulatives (NLVM) is a project which uses this approach to instruction in teaching mathematics while addressing the problem of student disengagement. NLVM is a National Science Foundation (NSF) supported project that provides uniquely interactive, web-based virutal manipulatives and concept tutorials to involve students, at every grade level. Through the use of manipulatives, students are actively engaged in instruction and are able to visualize relationships and applications. Topics covered are: number and operations, algebra, geometry, measurement, and data analysis and probability.