This learning activity will provide an introduction to the tools used for hardness testing of various materials through either in-class demonstration or a PowerPoint presentation and lab combination, depending on the preference of the educator and equipment available. Students will learn about the factors that affect the hardness of a material and explore the circumstances under which the same materials can have different hardness values. This module is intended for advanced high school or introductory college students and is intended to follow the MatEd 'Hardness of Brass' activity or other introductory hardness lesson. The activity can be completed in one class session. The document is available to download in PDF file format.