In this video lesson, students will achieve the following learning objectives: 1) Become familiar with the fourth state of matter, “plasma"; 2) Understand the concept of plasma: 3) Compare the four states of matter; and 4) Learn some applications of plasma. Before starting this video lesson, students should have knowledge about: 1) The three states of matter - solid, liquid, and gas - and the properties of each state and how matter can change from one state to another; 2) The structure of the atom - what does it consist of, and what are the properties of each component; 3) How a neutral atom becomes an ion; and 4) The basics of conduction of electricity. No materials are needed for this lesson other than playing the video module. A worksheet for segment 3 can be downloaded from this web page. The types of in-class activities suggested for the breaks between video segments include small group discussions and worksheet completion.