Self-Evident Truths
Euclid rallies a crowd with his first postulates, but loses them at the long, complicated parallel postulate.
Use this cartoon
Free for classrooms, worksheets, slides and other non-commercial use under CC BY-NC 4.0, with credit to Ben Orlin.
Cartoon by Ben Orlin, Math with Bad Drawings. https://cartoons.mathwithbaddrawings.com/2018-12-05-self-evident-truths/ (CC BY-NC 4.0)Transcript
Euclid (on a soapbox): "We hold these truths to be self-evident: that any two points can be connected by a line!" Crowd: "Yeah, Euclid!" "You tell 'em!"
Euclid: "That any line segment can be extended indefinitely!" Crowd: "Yes, Euclid!" "Preach, brother!"
Euclid: "That if two lines intersect a third such that the sum of the enclosed angles on one side is less than a straight line, they will intersect on that side of the line!" Crowd: "Um..." "You lost us, brother." "Maybe build up to that one, Euclid."