Question

Every _____ tessellates.

pentagon
hexagon
quadrilateral
octagon

Answer 1

what's " tessellates" ?

Answer 2

no idea

Answer 3

well... do you know what
pentagon
hexagon
quadrilateral
octagon
looks like?

Answer 4

pentagon

Answer 5

Tessellates means you can cover the x-y plane completely by repeating the same shape.
We cannot tesselate a pentagon, because the interior angle is 108 degrees, and there is no way its multiples make 360 degrees.
So one requirement is that the interior angle must be a sub-multiple of 360 degrees.

Answer 6

http://www.shodor.org/media/Z/D/V/iNmIzNTdhZDY0NjQyOWU3MTMwNjZhOTY2OTRiNmM.gif <--- an example of "tessellation"

meaning, when just using one shape alone
you can "gaplessly" fill out an area

that is, the shape around area tucks in with the others