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| The Cartesian Plane |
Two perpendicular lines, the x-axis and the y-axis, split the plane into four infinite quarter-planes, which are called quadrants. As mentioned earlier, the first quadrant has positive values for both its x and y coordinates. Quadrants are numbered using Roman numerals, so we label it I. Then we label the other quadrants, naming them with Roman numerals II, III, and IV, in counterclockwise order. As shown in the graph, QII has negative x-values, but positive y-values. QIII has negative x-values and negative y-values. QIV has positive x-values, but negative y-values. Even as, more and more frequently, time presents itself digitally, some students may wonder why the quadrants are not arranged clockwise. Some may be initially confused. For others, even if it makes sense at first, a clockwise orientation may feel more natural, and the draw of the familiar may provide an opportunity for error.
Teachers should expect to be questioned about this: “Why not clockwise?” The stock answer is, “That’s the rule.” Take the time to delve a little deeper. This response may sound to a young person like, “because I say so.” Dissatisfaction with explanations and confusion about them go hand in hand. A solid understanding of how to label the quadrants should enable your students to discuss graphing more efficiently. Graphing on the coordinate plane is a skill that will be immensely valuable throughout high school math and well into college courses, including and beyond multi-variable calculus and electro physics. The purpose of this convention and most conventions in general, is to avoid ambiguity. (And ambiguity can lead to chaos! Imagine if we didn’t have the convention of driving on only one side of the road.) 
Physicists in particular use the right-hand rule to navigate in three dimension
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