Problem solving and proportions related to leap day and Roman history! What's not to love? Beginning with a little history lesson about the Julian calendar, this activity brings together astronomy, European history, and proportions. For an extension, students pretend that they are Pope Gregory and must fix the Julian calendar.Want to learn more about calendars from around the world? Explore how different cultures have used the moon and/or sun, and how they have used leaps in our activity "Leap W