After running the GCK virtual fruit fly breeding lab for the first
time, I saw that it could be done in two ways, each of which has
parallels for teaching in areas other than biology:

Model 1. 3Ps
Assume that students are aware that heredity is (usually) thought of
in terms of genes and that this cannot be easily erased from their
minds.

Inform students that the underlying basis for any observed character
will be two genes, one of which may obscure the effect of the other.

Give the specific goal of the lab as experimenting so as to become
able to explain to oneself and to others the observed characters in
different crosses (vials) in terms of the two genes involved. This
involves Posing problems (how to cross flies to expose the genes
involved), Problem solving (how to explore, experiment, record
results, analyze them and proceed accordingly), and Persuading others
(to show you really understand).

Give the rationale for the lab as to learn deeply what seems clear
when you read it in a text book, but readily gets unclear or slips
away when you don't have any experience of what it means in actual or
virtual breeding experiments. (This is especially important if
students are to proceed to more complicated genetics and breeding
experiments, which was not the case for this computers in ed. class.)

Model 2. 5Ps
Ask students to dispell any idea that heredity is thought of in terms
of genes and ask them to simply start from the Phenomena they
observe. In particular, instruct the students not to take it as
given that heredity should produce distinct characters generation
afert generation. (Remember that height is not like that, and it is
perfectly conceivable that heredity could result in a blending of the
characters of the two parents.) Look for Patterns that interest or
intrigue you. Then proceed with the other 3Ps, as described above.

Inform students that the underlying basis for any observed character
will be systematic -- it won't change from cross to cross.

Give the specific goal of the lab as experimenting so as to become
able to explain to oneself and to others the observed patterns that
interest you. If those patterns break down as you explore further,
take note of that.

Give the rationale for the lab as to experience being a scientist,
even if you are not disposed to taking science classes. Indeed, this
is important for students who do take science, because it reinds them
that behind all the facts and theories they learn as established
there was a stumbling process of discovery of what had previously
been unclear or unknown. (Scientists aren't informed by Nature "that
the underlying basis for any observed character will be two genes,
one of which may obscure the effect of the other"!))

How did 9/27 lab fit into the two models?
I had model 2 in mind, but didn't see how much I would have to be
explicit about getting students to dispell any idea that heredity is
thought of in terms of genes and ask them to simply start from the
Phenomena they observe.

I saw model 1 as too like the demonstration lab that GCK gave you a
chance to avoid. I didn't appreciate the value of having students
learn deeply what seems clear when read in a text book.

Whichever way I go if I teach this in the future, I might add record
sheets which would have 5 columns: Character of male parent.
character of female, characters of offspring, in what proportions,
conclusions/Qs that follow from this.

A few extensions to other subjects
Model 1 could be applied in mathematics to students "discovering"
Euler's rule (relating edges to vertices in geometric shapes). Yes,
the teacher may know the answer, but students don't.
In English, it could be applied to discovering the effect of
different meters on the sound of poetry.
Other suggested extensions welcome.

Model 2 could be applied in history by finding some primary documents
and asking students to develop a historical account of whatever
phenomena they see in the documents. (Some guide on basic historical
method would be needed, like the 3Ps article for science.)
Similarly, in English, students could be given concordances of how
many times words appear in Shakespeare, The Origin of Species, or the
Bible.
Again, other suggested extensions welcome.

Not all of the suggestions above need involve computers, or some
might involve software that hasn't yet been written, but I hope you
my reflection has clarified the pedagogical issues behind using
something like GCK software.

Reactions and questions welcome,

Peter