I second what Marty recommends. When I started at my current school (630
students all girls) we had 1 physics class. We now have 8 first year
classes and 2 second year classes.
In addition to the "Wall" that Marty suggests I have former students come
back and talk to my classes. Last year a mechanical engineer alum who is
working for Rolls Royce came and talked about her experiences and travel
while working on the F136 engine. Another physics grad came and talked
about her graduate studies in biophysics.
Do some labs in the hallways. Yes the slinky lab could be done on the
floor of the lab but when in the hall the students passing by see what you
are doing. We also do a toy truck lab for constant motion in the hall and
bungee Barbie is a hit in the quad every year.
You also have to convince the counselors that physics should be part of
any college prep curriculum. The first year I bombarded them with
articles and anecdotal evidence that physics should be a part of the
college prep schedule. We also worked closely with the math department to
tie our algebra/trig physics to their precalc curriculum. They then helped
sell physics.
Like Marty, in some ways this was self serving. I could drop a freshman
general science for every additional physics section. The bottom line
however is that it is IMHO good for the students. We went from one or two
MSE (math science engineering) majors a year when I came to about 12% of
the class majoring (and finishing) an MSE major.