Plot B-V versus magnitude for each star on a piece of graph paper. Use a different plot or different color for each cluster. Your X-axis is the color (B-V) and runs from -0.1 to +1.5 in both plots. Your divisions should be about 0.1. The y-axis is the apparent magnitude and runs from 25 to 5. Don't forget that magnitudes are backwards, so smaller numbers mean brighter stars. So, your Y-axis will run backwards - larger numbers on the bottom, smaller numbers on the top (see Lab 6 graph template).