I first created a static sketch with a loop of hollow squares. Then I thought about making it more dynamic by rotating and scaling it. I created two sliders , one controlling the rotating speed and the other controlling the scaling speed. and one button to generate a random color for the squares. My original intention for creating the slider was to use if (mouseIsPressed){} because it is used to test if mouse is being held down. So when I'm holding down the mouse dragging the slider, the code inside if (mouseIsPressed){} should be executed. However, I don't know why it did not work. So I referred to the example code for slider and it worked like a charm.