In this lesson, Nick Palazzolo, CPA, breaks down the concept of the relevant range, a critically important topic for understanding how variable costs behave within certain levels of production. He uses straightforward language and real-life examples to clarify that within the relevant range, the costs increase consistently in proportion to the number of units produced. Nick elaborately illustrates the idea with graphs, showing a linear increase in costs within this range, and contrasts it with the inconsistent cost behavior when production falls outside of this range. This explanation is designed to demystify the topic and ensure comprehension of how costs vary with production levels, knowledge that's essential for tackling multiple choice questions on this subject.