You will need : B3 pencil (or a HB is fine), paper, rubber, an apple and a lamp or other bright light source.  Because I didn’t have a lamp to hand when I was preparing this tutorial I just drew an imagined torch up in the top right of the page and put arrows showing where the light was falling.   You can do that too…. or even try a different fruit instead.  Fruit is a handy image to draw because there’s usually some around and it doesn’t move when you shout at it!!