The students are given a copy of the HR diagram with 
evolutionary tracks (file tracks.ps), and 3 data sets (track1 -
track3). The tracks on the diagram are labelled 
with numbers indicating mass in solar masses. 

Their job is to locate all (T,L) points from datasets on the 
diagram and to label them with evolutionary times
(the times are provided in track* files).

File tracks_solution.ps contains the diagram with all points 
marked on it.

The evolutionary times in the data are expressed in years
and printed in standard Fortran notation 1.234e+12.
I am not sure if the students would understand this writing; 
perhaps it would be better to express all those times in
millions of years.