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...

Young scholars explore the concept of angles formed by parallel lines.They graph two parallel lines cut by a transversal, then measure the angles formed by the transversal and record the data in a table. Learners make conjectures about...

Learners investigate properties of similar figures. In this properties of similar figures lesson, pupils construct similar figures using Cabri Jr. They dilate their figure to create a similar one, and discuss the relationships between...

Young scholars construct inscribed angles using Cabri Jr. They draw a circle on their graphing calculator, then construct an inscribed angle and measure its angle measures. Learners drag the inscribed angle around the circle. They make...

How do you know if a pair of triangles are congruent? Use the instructional activity to help class members become comfortable identifying the congruence criteria. They begin with an exploration of ASA and SSS criteria through...

Pupils explore the concept of angles and transversals. They construct parallel and non-parallel lines cut by a transversal using Cabri Jr. Learners then determine which angles are congruent and the relationship of angles when two lines...

Breaking the rules is one thing, proving it is another! Learners expand on their previous understanding of congruence and apply a mathematical definition to transformations. They perform and identify a sequence of transformations and use...

High schoolers explore the concept of congruent triangles.  In this congruent triangles lesson, students use Cabri Jr. to construct two congruent triangles using circles.  High schoolers determine if the two triangles are...

Students measure angles using a protractor. In this geometry lesson, students solve for the missing angles using equations set to the theorem of triangles. They measure missing angles through construction and identify congruent angles.

High schoolers will investigate geometric construction in this geometry lesson. Your pupils can explore the basic construction of copying an angle, using the constructions tools of Cabri Jr.

Eighth graders explore congruent and similar figures.  In this eighth grade geometry lesson plan, 8th graders use geoboards to create congruent and similar figures and explore the relationships between the sides and angles. 

Students use web applet to create congruent triangles. In this geometry instructional activity, students differentiate between congruent and similar. They create shapes online and drag those shapes around to create visuals of triangles.

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...

Learners investigate the process necessary to construct regular polygons. They explore the degree measures of the angles in a regular polygon. Using this information and technology in the form of Cabri Jr., your pupils will construct...

Students investigate triangles and congruences. In this geometry lesson, students differentiate between inductive and deductive reasoning. They differentiate between similar and congruent triangles.

Learners differentiate between similarity and congruence using polygons. In this geometry lesson, students label triangles based on their properties. They find missing sides and angles using the interior sum theorem.

Pupils investigate angles through construction. In this geometry lesson, students use a protractor to identify the measurement of an angle. They identify angles cut by a transversal and two parallel lines.

Tenth graders investigate the theorems of ASA, AAS, AAA and ASA. In this geometry lesson, 10th graders discuss the theorems of triangles and how it is used to solve for missing sides or angles. They review how two angles are formed by...

Students view a right triangle displayed by the teacher. Students measure legs and the interior angles of the triangle. They look for a pattern or relationship between the legs and angles. Students use pegboards and string to create more...

Students identify lines, and line segments. In this geometry lesson plan, students divide line segments into equal congruent parts. They complete a laboratory activity dealing with lines and segments.

Students construct midsegments. In this geometry lesson plan, students make conjectures and apply properties of triangles to solve problems. They complete an activity on the computer.

Students investigate the relationship between angles and their sides. In this geometry lesson, students prove why SSA does not work as a true angle side relationship theorem.

The problem seems simple: find the area of the equilateral triangle whose sides are each length 1. In fact, this same problem is solved in 8th grade, addressing a different Common Core standard, using the formula for area of a triangle...

A diameter is the longest chord possible, but that's not the only relationship between chords and diameters! Young geometry pupils construct perpendicular bisectors of chords to develop a conjecture about the relationships between chords...