Part 2 of Unit 3 often focuses on how stars move across the diagram as they age.

For the math/logic questions on the quiz, remember this formula (Stefan-Boltzmann Law conceptually):

Crucial Quiz Tip: The temperature scale is . Hotter blue stars (30,000K+) are on the left , and cooler red stars (3,000K) are on the right . 2. The Four Major Regions