Area Animation Using Vertical Strips
Area of a region bounded by x-axis, two ordinates, and a function using Riemann Sums is the starting point of a definite integral . Through this GeoGebra applet we animate area using the notation of infinitesimal width of a strip, namely dx,. This also leads to the same formula in terms of definite integral. However, this is a more versatile approach for allowing all kinds of variations and setting up basis for applications of integral to finding arc length, surface area and volume of solid of revolution, and further in the applications of double and triple integrals.
For more on finding area check my online book
"Flipped Classroom Calculus of Single Variable"
https://versal.com/learn/vh45au/