Description: Sal uses virtual manipulatives to identify figures that scale proportionally. So this slider, shape B right over here, the slider for shape B is not creating scale copies of itself, it's only increasing the width, not the height. While shape A, it looks like it is increasing both the width and the height, so that would be a scale copy. So once again they say, "Drag the sliders."*Teacher Advisor is 100% free.