This course will introduce age hardening and how to use a phase diagram to identify an alloy that is eligible for age hardening. The key factors that affect nucleation and crystal growth will be investigated. In addition, an introduction to polymer science will be given. The key differences between thermoplastic and thermosetting polymers will be introduced. Strengthening mechanisms will be introduced. We explore what happens to the properties of a polymer as you increase or decrease the extent of cross-linking. major polymer synthesis methods will be shown. We will review polymer selection for various applications. In addition, how structural properties vary with temperature will be presented. We explore the significance of the glass transition temperature of a polymer to its thermal and mechanical properties.