Universal Principles of Design - Usability

How can I enhance the usability of a design?

Principle 1 - 80/20 Rule

When I first began reading about this rule, I was surprised by how confusing it sounded.  However, after looking at the example of the Microsoft Word toolbar and how the 20% of its functions that compose 80% of its use are shown as icons, while the 80% that only compose 20% of Word's use are tucked away in drop-down menus, I found it much easier to understand.  This reminds me of the manner in which I organize my classroom materials.  I have a desk organizer that holds a dozen or so hanging file folders and a filing cabinet that holds hundreds of hanging file folders.  The folders that I access regularly (i.e., the resources for a chapter that I am teaching) are in the smaller, handy organizer on my desk, while those that I don't access regularly (i.e., students' past grades records) are tucked away in my filing cabinet.

Principle 2 - Confirmation

While the dialog boxes in computer software often drive me crazy, I have often had cases in which that confirmation was welcomed (i.e., are you sure you want to delete all music from your iPod, NO!  CANCEL!).  I use similar methods with my students in long class activities.  I often write in certain checkpoints in their work.  For example, "Once you finish problems #1 & 2, come to me to check your answer before moving on to #'s 3-10."  This prevents my students spending large amounts of instructional time working through activities with incorrect comprehension that I could have detected earlier.  By confirming their comprehension (or lack thereof) I can be confident in them continuing (or help them get on track).

Principle 3 - Cost-Benefit

This is something that designers--of all sorts--need to take into consideration and often do not: Is the effort needed to complete this process (the cost) worth it to obtain the result (the benefit).  As a designer of instruction, I often consider this with my lessons.  It could be a consideration of, "Is this long dry teacher-led instruction worth the learning that it will result in?  Or will this cost lead to student boredom and apathy before the benefit is reached?"  I also do the same thing for fun things in class.  For example, "Is the amount of time that this game (or lab or investigation takes) worth the learning that it will result in (benefit)?  Or does it take up so much time that it doesn't account for the benefit?"

Principle 4 - Mental Models

I also need to take System Models and Interaction Models into account when designing class activities, especially those that are investigations.  Often, I can design an investigation that makes total sense to me (its system model, how it should work), but result in surprising mass confusion from my students (its interaction model, how it actually works with when interacted with).  In these cases, I look back to the 3rd principle I discussed, Cost-Benefit!  I also liked the example here of anti-lock braking systems.  I can remember when I was 16 and first driving--a pick-up truck, no less--sliding through a snowing parking lot thinking to myself, "Do I slam on the brakes?  Do I pump the brakes?  Do I have ABS?"

Principle 5 - Readability

This is a major concern for teachers--making sure that their instruction of new material is accessible to their students.  While the concept may be new and difficult, the reading involved should not be.  I also enjoyed viewing the Edward Fry's Readability graph, though I think that it is easier to simply use Microsoft Word or OKAPI to determine Readability levels.  Regardless, it is an important thing to take into consideration.