CK-12 Foundation
Bisectors of Line Segments and Angles: Cut a Line
Geometric constructions build relationships —by simply manipulating simple tools. An interactive lesson presents a completed construction of a segment bisector and has learners analyze the important aspects. Ultimately, they should be...
CK-12 Foundation
Congruent Angles and Angle Bisectors: Bisecting Pepperoni Pizza
Who doesn't like pizza? A creative lesson uses a piece of pizza to explore angle bisectors and congruent angles. Young scholars work through a simulation to create congruent slices of pizza by analyzing an angle bisector. They then...
CK-12 Foundation
Bisectors of Line Segments and Angles: Cut an Angle
Explore constructions through an interactive online lesson. Given an example of an angle bisector construction, learners investigate the markings to determine the method used. Challenge questions help solidify the steps.
Curated OER
IGD: Perpendicular Bisector
Students draw perpendicular bisectors. In this perpendicular bisectors lesson, students identify the perpendicular bisector in a polygon. They use web tools to create and measure perpendicular bisectors. Students...
EngageNY
Congruence, Proof, and Constructions
This amazingly extensive unit covers a wealth of geometric ground, ranging from constructions to angle properties, triangle theorems, rigid transformations, and fundamentals of formal proofs. Each of the almost-forty lessons...
Curated OER
Perpendicular Bisector of a Line Segment
High Schoolers investigate the perpendicular bisector of a line segment. They use Cabri Jr. to construct the perpendicular bisector of a segment. The dynamics capabilities of Cabri Jr. allow your learners to observe the lengths of the...
Curated OER
Circles and Angles
Students identify tangents, chords and secants. In this geometry lesson, students graph circles and identify angles created by secant lines, tangent lines and chords.
Curated OER
Investigating a Point on an ANgles Bisector
Students investigate points and angle bisectors. In this geometry lesson, students define angles, bisectors and perpendicular bisectors. They analyze angles and bisectors using Cabri software.
Curated OER
Perpendicular Bisector Theorem
High schoolers construct perpendicular bisectors using Cabri Jr. on their graphing calculator. They then construct conditional statements about perpendicular bisectors along with their converse, inverse, and contrapositive.
Mathematics Vision Project
Circles: A Geometric Perspective
Circles are the foundation of many geometric concepts and extensions - a point that is thoroughly driven home in this extensive unit. Fundamental properties of circles are investigated (including sector area, angle measure, and...
EngageNY
Characterize Points on a Perpendicular Bisector
Learn transformations through constructions! Pupils use perpendicular bisectors to understand the movement of a reflection and rotation. They discover that the perpendicular bisector(s) determine the line of reflection and the...
Curated OER
Special Triangles and Circles
Students investigate special triangles and circles. In this geometry lesson, students construct a perpendicular bisector and discuss angles of a triangle. They find the angle bisectors, vetex and the types of circle constructed.
Curated OER
Inscribing a Circle in a Triangle
Pupils investigate inscribing a circle in a triangle. They use Cabri Jr. to draw a triangle, locate the incenter, and use the distance from the incenter to a side of the triangle to inscribe a circle. The dynamic nature of the geometry...
Curated OER
Show Me the Way To Go Home
Learners place a pencil perpendicular to the ground and trace its shadow between 11:30 AM and 12:30 PM. They measure the length of the shadow, periodically over several hours, in either English or Metric units. Using the data, they find...
Curated OER
Geometry on a Grand Scalle
Students, in groups, construct different angles and shapes on a large scale using string and chalk.
Curated OER
Contructions and Conjectures
Students make constructions and conjectures. In this geometry lesson, students construct right, acute and obtuse angles using a straight edge and a protractor. They investigate parallel lines and the angles formed by the angles.
Curated OER
Constructing Perpendicular Bisectors
Tenth graders investigate parallel lines and the angles formed when cut by a transversal. In this geometry instructional activity, 10th graders construct perpendicular lines and discuss midpoint, segments and perpendicular bisectors....
Curated OER
Incenter of a Triangle
Tenth graders explore the properties of the incenter of a triangle. In this geometry lesson, 10th graders construct a triangle and the angle bisectors of each angle. The dynamic properties of Cabri Jr. allow students to locate and...
Curated OER
Isosceles Triangles
Students identify the properties of an isosceles triangle. In this geometry instructional activity, students find the midpoint, median and angle bisector of a triangle. They construct angle bisectors and measure missing angles.
Curated OER
Incenter of a Triangle
Tenth graders find the incenter of a triangle. In this geometry lesson, 10th graders define the way to create an incenter with an angle bisector. They differentiate between incenter and incircle.
Curated OER
Orthocenter Of a Triangle
Students find the orthocenter of a triangle. In this geometry lesson plan, students identify where the altitudes meet in a triangle. They use Cabri software to explore acute, obtuse and right triangles.
Curated OER
Concurrent Lines in Triangles
Students explore the concept of concurrent lines in triangles. For this concurrent lines in triangles lesson, students work in groups to investigate properties of concurrent lines in acute, right, and obtuse triangles. Students use a...
Curated OER
Triangles with Collinear Circumcenters
Students identify the circumcenter of a triangle. In this geometry lesson plan, students construct a perpendicular bisector using a straight edge and a compass. They differentiate between triangles and collinear points.
Curated OER
Constructing Perpendiculars
Students construct perpendicular lines. In this geometry lesson, students use a compass and straight edge to do construction. They start from a point to a line.