Lesson 3: 1-3: Locating Points and Midpoints

When are two segments congruent?
How is the midpoint determined between two points on a number line?

Midpoint
Segment Bisector

G.CO.1
Know precise definitions of angle, circle, perpendicular line, parallel line, and line segment based on the undefined notions of point, line, distance along a line, and distance around a circular arc.
G.CO.12
Make formal geometric constructions with a variety of tools and methods (compass and straightedge, string, reflective devices, paper folding, dynamic geometric software).

The midpoint of a segment is the point halfway between its endpoints. The midpoint of a segment with endpoints a and b on a number line is the sum of a and b divided by 2. The Midpoint Formula is used to find the midpoint of a segment on the coordinate plane. Similar methods are used to develop a process for finding a point a fractional distance from one endpoint on both a number line and the coordinate plane.

Lexington, Nebraska is located on Interstate Route 80. It is the midpoint of Interstate 80, 1450 miles from its endpoints, San Francisco, CA and Teaneck, NJ.

Students approaching grade level can be given practice problems in small groups to work with other students or directly with the teacher.
Students beyond grade level can make deeper connections in the following way: students sketch three different segments on the coordinate plane that each have (0,0) as a midpoint. Write the coordinates of the endpoints of each segment, and make connections between all of the segments.

Formative Assessment

Textbook in class

Access online textbook and resources through class link.