We describe a study of period changes in 59 RR Lyrae stars, using times of maximum brightness from the GEOS database. The work was carried out by outstanding senior high school students in the University of Toronto Mentorship Program. This paper is w
ritten in such a way that high school or undergraduate physics and astronomy students could use it as a guide and template for carrying out original research, by studying period changes in these and other types of variable stars.
