If you want to get the "wow" factor from a science project.... use a gui of some sort. Of course I recommend Tk or Gtk2. ;-) How about something cool like simulating an instrument on a satellite and logging the data on a strip chart recorder on earth? See Tk Realtime data aquisition
Maybe monitor solar wind? You could connect right to the spacecraft data-servers like solar data server
Have the data recorder and maybe make a 2-d visualization of the magnetosphere at the current moment, that could be done with animated gifs.
Or how about the Superformula and a Tk visualization tool? See SuperFormula with gnuplot and Tk It could be useful in nano-technology, or a math oriented project exploring the polar coordinate system.
Both of those should inspire wonder in 9th graders.
One that is more real-life, and could lead to a career, is setup a linear research project (optimizations done with matrices and linear equations) to find the optimal manufacturing/ordering/warehousing setup for something cool like emergency food distribution. Factors like proximity of warehouses to likely disaster areas, local costs, road availability, expiration dates, etc. You could setup a map, and determine where the warehouses should be built and what capacity at each location. But that is getting more like work, and not a fun project.