It could be that they don't understand (clearly enough) the material that
you present immediately before you present the arrays. Is the following
accurate?
They can handle the basic drawing canvas.
Draw a line from here to there.
Draw a bezier curve with these parameters.
Draw a figure with these parameters.
They can handle iteration.
Draw a line. Move down.
Draw a line. Move down.
They can barely handle the two notions together.
Draw a complex figure here, then change the parameters.
To understand that, they need to be very clear about:
1. The input parameters
2.