Instructional design
is a crucial component of instruction -- and, regretably, is often overlooked.
When designing instruction, the advice related to instructional design
is "Don't teach without it." To read all about it, see the
current textbook on this topic: The
Systematic
Design of Instruction (5th edition) by Dick, Carey & Carey.
A 6th edition is forthcoming. The link is FYI -- see the book vendor
or library of your choice.