A net for a cylinder object consists of 2 circles and a rectangle.
think about it this way
a cylinder will be like a soda can, so you get an empty soda can, if you cut the circular top and bottom, you end up with ⃝ and ⃝.
then if you with a knife cut the leftover vertically and lay it flat, you're left with ▯.
so the soda can was really just [tex]\bf \bigcirc \boxed{\stackrel{}{\qquad }} \bigcirc[/tex]