This is an Educational research endeavor to apply Robert Gagne''s Instructional Design to infuse Thinking and Problem Solving skills into the instructional process of a specific discipline. It is an attempt to enhance the process of Thinking and Problem Solving skills among secondary school students. The Instructional lessons designed intended to achieve the selected learning outcomes, viz., Concept learning, Principle learning and Problem Solving learning which in turn intended the enhancement of Thinking and Problem Solving Skills in general. The Effectiveness of the Gagne''s Instructional Design was tried out on students of High, Average and Low Intelligence. This study has implications for the design and development of Instructional Materials in line with Gagne''s Instructional Design to achieve different learning outcomes. This has been found to be a systematic strategy to improve classroom instruction across various disciplines. The contents of this book are of much use to the school teachers and researchers interested in Designing Instruction and involved in Thinking and Problem Solving Research.