You will receive a .pdf file suitable for printing as a 18"x24" poster (I recommend shortrunposters.com).
This poster features two different faces of which the eyebrows, nose and mouth represent the 4 linear functions' slopes. The eyes are + and - signs, under the nose is a "U" to show "undefined" slope and the cheeks are 0s for "zero slope." On the bottom is a description in algebraic terms.
My students LOVED this poster. I put it up before we talked about slope, and told them they would "meet" the kids the next day. They referred back to it often and drew the faces on their tests when it had to be removed for state testing.
If this color combination is not pleasing to you, check back for more color choices in the future!