Probability and the Observable Universe

Basic high school Algebra is often taught in relative abstraction from topics relevant to students’ lives, but has the potential to be very concrete and, as a result, more engaging for all students. Probability is a concept often left for the end of the year and taught with very little cohesion to the rest of the topics in Algebra. Additionally, the examples provided in textbooks are often low-level and can lack relevance for students. This unit however, would allow students to use their own personal experiences in their own specific circumstances in conjunction with a new grasp on probabilistic thinking in order to gain a more meaningful understanding of probability in the context of the universe.
This unit is designed for my 9th grade Advanced Algebra classes, which meet five times per week for 48 minutes per day, to complete in around two and a half weeks. Students are expected to have completed most of Algebra 1 by the time they reach this unit and should have a strong grasp on arithmetic and the ability to reasonably argue whether or not a determined solution makes sense in the context of a given question or problem. Prior knowledge of astronomy or compound probability is not required, but students should have a firm grasp on how to convert between fractions, decimals, and percents.