Perp Lines are Perfect
Objective: SWBAT find the perpendicular bisector of a line segment and construct perpendicular bisectors using a compass and straight-edge.
Big Idea: Algebra and geometry intersect, please pardon the pun, in this lesson on perpendicular bisectors.
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Do Now
Students will complete two warm-up questions that require them to use pre-requisite skills of writing equations of perpendicular lines and also finding the midpoint of a line segment.
The student notes provide scaffolded notes and examples for students to complete two constructions of perpendicular lines through a point on a line and a point not on the line. These videos explaining construction from a point on a line and not on a line are a great resource for in-class instruction and also for absent students (MP 5).
CCSS for Geometry requires that students prove how and why constructions work. The construction in this lesson requires students to have knowledge of congruent triangles (the next unit) so teachers should make students that we'll be proving why these constructions work in future lessons (MP 7).
Exit Ticket
Students will find the perpendicular bisector of a line segment given 2 endpoints. This Exit Ticket can easily be collected by asking students to write their work on a separate piece of paper or a post-it note.
