This paper addresses the need for enhancing our awareness of user-centered design in educational technology through a more explicit and systematic alignment between the needs of educational technology users (learners and educators) and the affordances provided by the technology. First, we define the term "affordance" and discuss it from the perspectives of cognitive psychology and user interaction design. Next, we propose a taxonomy of functional affordances that builds on prior research and reflects the current trends in the design of educational technologies. The paper is concluded with an illustration of how explicit alignment of needs, abilities, and affordances can inform the evaluation of an educational technology designed to support dyslexic readers. The four-step framework applied in this analysis helps (a) define user needs, (b) identify a potentially appropriate technology, (c) understand the abilities the technology affords and (d) align technological affordances with the specific needs of the target users. This framework is a step toward increased recognition of the importance of user-centered design of educational technologies; it provides the needed guidance and structure for aligning needs, abilities, and affordances during the design, implementation, and evaluation of technologies for learning and teaching.