Area of a circle visual proof

I think showing how A = PI r^2 relates to the area of a rectangle would be a valuable addition to the intro to circles in the grade 7 math course. Right now it's a bit unsatisfactory how the conclusion is reached, only something about "the radius can be used" is mentioned. Please consider inclusing a proof such as this to help with intuition https://m.youtube.com/watch?v=-UBLutigNMM&pp=ygUQYXJlYSBvZiBhIGNpcmNsZQ%3D%3D thank you :)