There are over 100 instructional design models that help curriculum developers visualize problems and break them down into manageable units to facilitate knowledge transfer. The most common is the ADDIE model, which incorporates five phases: analysis to clarify requirements, design for planning strategies and objectives, development to compile information, implementation to apply the curriculum, and evaluation to review effectiveness through assessments. Other iterative models continually evaluate and improve the design through testing prototypes or additional steps. Effective instructional designers understand cognitive learning processes and motivation to competently design engaging learning resources.