Updated Principles (markdown)

Principles.md

@@ -12,13 +12,15 @@
 Extracted from her presentation at Camp Smalltalk 50th Anniversary.
 * The context of a learning environment based on modeling is as much about understanding how an existing model works, as it is constructing a new model. As a consequence, the ability to read an implementation **matters** -- Hello Smalltalk.
 
-* **Smalltalk kit**, specific set of interacting objects and theways in which those objects relate to one another, and how they can be accessed and refined. I also use the term **modeling* rather than **programming,** since, as you now know, creating, sharing, and challenging the veracity of models comprises a particular approach to learning
+* **Smalltalk kit**, specific set of interacting objects and the ways in which those objects relate to one another, and how they can be accessed and refined. I also use the term **modeling* rather than **programming,** since, as you now know, creating, sharing, and challenging the veracity of models comprises a particular approach to learning
 
-* So an important quality of this kit (Programming by Rehearsal) is that it is always working, always displaying what the model
-represents.
+* So an important quality of this kit is that it is always working, always displaying what the model
+represents (_on Programming by Rehearsal_).
 
-* What also makes **ThingLab** Smalltalk kit so interesting is its view that constraints, whether equations to be
+* What also makes this kit so interesting is its view that constraints, whether equations to be
 solved or relations to be maintained, can express partial information, can be combined with other
 constraints, can be general purpose in the sense of their properties, are declarative, and can be
 searched and experimented with. So, these represent an important class of base objects we would
-need in a modeling environment.
+need in a modeling environment (_on ThingLab kit_).
+
+* It would be a mistake to assume that there is just one virtual world of simulation as generality often proves to make things harder for beginners (_on Alternate Reality kit_).