University of Oregon
Determining Properties of Stars
An excellent website detailing how a star's properties can be determined, and how these properties lead to the way a star is classified.
NASA
Nasa: Imagine the Universe: How Big Is That Star
This 2-5 day lesson plan investigates the diameter, radius and mass among several stars in order to understand stellar behavior, particularly in a binary system.
Enchanted Learning
Enchanted Learning: Star Types
EnchantedLearning.com provides a thorough examination of the how stars are classified. The different types of stars are named and defined. Text is supplemented with pictures and drawings. A great introduction to the world of stars.
CK-12 Foundation
Ck 12: Earth Science: Life Cycle and Classification of Stars Study Guide
[Free Registration/Login may be required to access all resource tools.] This study guide summarizes key points about types of stars and he life cycle of a star. Includes a few questions to check for understanding.
Other
Sky Server: Color
SkyServer answers why stars have different colors and shows what you can learn by studying the colors of stars, galaxies, and other objects.