1. **Problem:** Teach the 4 quadrants in a full $360^\circ$ circle and draw them clearly. 2. **Formula / rule:** A full turn is $360^\circ$, and the coordinate plane is split by the axes into 4 quadrants. 3. **Quadrant rules:** - **Quadrant I:** $x>0$ and $y>0$. - **Quadrant II:** $x<0$ and $y>0$. - **Quadrant III:** $x<0$ and $y<0$. - **Quadrant IV:** $x>0$ and $y<0$. 4. **Angle ranges in a $360^\circ$ circle:** - **Quadrant I:** from $0^\circ$ to $90^\circ$. - **Quadrant II:** from $90^\circ$ to $180^\circ$. - **Quadrant III:** from $180^\circ$ to $270^\circ$. - **Quadrant IV:** from $270^\circ$ to $360^\circ$. 5. **Important rule:** Angles are usually measured counterclockwise starting from the positive $x$-axis. 6. **Easy memory:** - Right and up = Quadrant I. - Left and up = Quadrant II. - Left and down = Quadrant III. - Right and down = Quadrant IV. 7. **Final answer:** The circle is divided into 4 quadrants: I, II, III, and IV, with angle ranges $0^\circ$-$90^\circ$, $90^\circ$-$180^\circ$, $180^\circ$-$270^\circ$, and $270^\circ$-$360^\circ$.