Day 23 – Tangent Lines

Physics 11 – There was about 15 minutes of direct instruction in today’s lab. I wanted students to learn about tangent lines, so I worked through a set of arguments that would communicate how a tangent line on a position-time graph is the instantaneous velocity at that point.





So some kids get this pretty quick.  A lot of students, when asked to draw tangent lines on their position-time graphs, start drawing lines between two points. I really have no explanation for this.  While I can understand a student having a fuzzy idea of what a tangent line represents, it’s difficult to say why they would read the above and draw a line that crosses their curve in two points.