Make observations of Saturn's position relative to Castor and Pollux every other week or so, during the semester. Make a table, giving for each observation:
(1) the date (and time, if recorded) of the observation
(2) The distance from Castor to Pollux, in inches and hundredths of an inch (you can use graph paper like you used for the Mercury project to do the measurements)
(3) The distance from Pollux to Saturn, in inches and hundredths of an inch
(4) the ratio of distance 3 to distance 2, to 3 digit accuracy
(5) The angle at Pollux, between the direction to Castor, and the direction to Saturn (use a protractor to measure the angle)

On a single picture/graph, show all the positions of Saturn, by placing Castor and Pollux at a fixed distance (one or two inches apart should work, depending upon how many observations you have, and how accurate they are), then, for each of the recorded observations, drawing a line in the direction from Pollux which gives the angle (5) listed above, and marking on that line, the position of Saturn, calculated by multiplying the distance between Castor and Pollux by the ratio of distance (4) listed above. (If the distance between Castor and Pollux is 1 inch, no multiplication is required, but that might make the graph/picture too small.)