One of the most useful graphs that astronomers use it the Hertzsprung-Russell Diagram. Developed in 1911, it is a plot of star color/temperature vs. Absolute Magnitude (brightness of stars calculated to be at a distance of 10 parsecs). This activity consists of 5 pages that should be duplicated and distributed in quantity for the class. Two additional pages [in cream sheets] are the answer key for teachers.
Students will learn about the color/temperature classification of stars. Also, the activity discusses star brightness and differentiates between relative brightness for stars as we see them and Absolute Magnitude for stars considered to be at a distance of 10 parsecs from Earth.
Students are then given a chart listing 25 of the closest stars along with both classification numbers for each. Using this information, students are asked to plot all 25 on the H-R diagram and consider the meaning of what has been plotted.