Tasks, Abilities, and Aptitudes

How do teachers design a sequence of tasks that sustains learner effort to use the L2 (second language), from beginning to end, and which simultaneously leads to L2 learning and development?  As a response, this volume presents connections among three areas of language learning-tasks, abilities, and aptitude. For research into these areas to be cumulative, and the pedagogic application during instructional systems design to be made clear, the author proposes a working taxonomy of task characteristics that can be linked to measurable differences in the abilities learners bring to task performance.