The idea that you need physics to teach HS bio and chem seems to be based
on a fallacious idea of what should be taught in those other science
classes.
You really do not need much physics to teach intro chemistry. You need
the basics of electrostatic attraction (not even Coulomb's Law numerically)
and energy. But energy is as much a chemistry concept as a physics one and
can just as well be taught in an introductory chem class.
The push for physics first is that it will enable students to understand
"modern" chemistry. But the quantum mechanical approach to chemistry would
be beyond high school students and inappropriate for them whether or not
they knew high school physics. The students would still be memorizing rules
for number of electrons in each orbital without any comprehension.
There is much worthwhile though provoking problem solving in classical
chemistry if the courses are appropriately structured. Stoichiometry, acids
and bases, titration, and solubility can all be taught in a meaningful and
challenging way that does not require physics. These are concepts that
students can understand and actually think about. And the pure memorization
aspects of chemistry - symbols, nomenclature, polyatomic ions - would still
be there.The usual high school chemistry curriculum may not be much of a
vehicle for intellectual growth, but that is because of the way it is taught
and not because of a lack of physics pre-requisites. Would the high school
chemistry curriculum suddenly drop its inordinate emphasis on significant
figures if the students knew physics?
There are also many challenging experiments high school biology students
can perform and historical experiments they can anlyze - without physics.
And what if the students had physics? Would the teachers then bypsass
teaching classification, plant structures, and mamilian physiology. Would
the students suddenly be able to understand the Krebs cycle or would it
still be memorization?
I have actually twice been in a situation where I suddenly had to
suddenly take over an eighth grade science class and both times I consented
only if I could experiment with teaching them physics. We used ticker tape
timers and Pasco motion sensors. We experimentally "derived" Newton's second
law and conservation of momentum. It was worthwhile for most (not all) of my
students. But they did not learn what my eleventh graders do.
And even my better eleventh graders have trouble with the concepts.
Scratch them a bit and you will probably be as horrified as I am about how
tenuous their understanding really is. Then ask yourself how much a ninth
grader seems to learn in physics is actually deep comprehension and how much
just all that much more a thin veneer.
To me, the paradigm for ninth grade physics is someone who told me he
teaches vector components to ninth graders by telling them to press the
buttons labeled sine and cosine on their calculators and that they will
learn later what these buttons mean.