Curated OER
Inscribing a Square in a Circle
Inscribing a square in a circle brings up a number of interesting geometry topics including triangle congruence and how to prove a quadrilateral is a square. This activity is followed up by finding the area of the square and determining...
Curated OER
Lines of Symmetry
Fourth graders identify lines of symmetry using reflections and then construct figures that have one or more lines of symmetry. In this symmetry lesson plan, 4th graders use sets of shapes, pattern blocks, a mirror, and more.
Curated OER
Concurrent Lines in Triangles
Students explore the concept of concurrent lines in triangles. In 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...
Inside Mathematics
Circles in Triangles
Challenge the class with inscribed circles in triangles. The assessment task requests class members use their knowledge of circles and right triangles to prove two triangles are congruent. They go on to utilize their knowledge of...
EngageNY
Reflections
Facilitate creativity in your math class as individuals learn the definition of a geometric reflection and correctly construct a model, as well as its reflected image. They use a perpendicular bisector and circles to elaborate on...
EngageNY
Mid-Module Assessment Task - Geometry (Module 1)
How do you prepare class members for the analytical thinking they will need in the real world? An assessment requires the higher order thinking they need to be successful. The module focuses on the concept of rigid transformations...
EngageNY
Tangent Segments
What's so special about tangents? Learners first explore how if a circle is tangent to both rays of an angle, then its center is on the angle bisector. They then complete a set of exercises designed to explore further properties and...
EngageNY
How Do Dilations Map Angles?
The key to understanding is making connections. Scholars explore angle dilations using properties of parallel lines. At completion, pupils prove that angles of a dilation preserve their original measure.
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...
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...
Curated OER
Math: Shapes and More Shapes
Students locate lines of symmetry in regular polygons and predict the number of lines of symmetry in an octagon. In three different polygons, they construct all lines of symmetry and after making their prediction about the octagon,...
EngageNY
Solve for Unknown Angles—Angles and Lines at a Point
How do you solve for an unknown angle? For this sixth installment of a 36-part series, young mathematicians use concepts learned in middle school geometry to set up and solve linear equations to find angle measures.
Curated OER
Math: Symmetry and Similarity
Pupils describe the differences between congruence and similarity. After explaining the motions that indicate congruency of two shapes, they complete worksheets to draw lines of symmetry and similar shapes. With straws and twist ties,...
Curated OER
Reflections
Fifth graders create a reflection of a poygon using a Mira. They discover that a line connecting a vertiex of a polygon and the corresponding vertex of its reflection is perpendicular to the line of reflection. Students create a glide...
Curated OER
Tangent Properties
Students explore properties of tangent lines. In this properties of tangent lines lesson, students discuss the perpendicular relationship between a tangent line on a circle and the circle's radius. Students use that relationship to...
Curated OER
Fun With Symmetry
Students manipulate shapes to find multiple lines of symmetry. They use color to visualize the lines of symmetry.
Curated OER
Symmetry of Road Signs
Students identify symmetry in road signs. In this geometry lesson, students explore objects in the real world for symmetry. They perform translation, rotation and reflection.
Curated OER
Constructions of Isosceles and Equilateral Triangles
Pupils explore the difference between drawing and constructing a triangle utilizing The Geometer's Sketchpad on the computer. They create, develop and script constructions for both isosceles and equilateral triangles. Each student has to...
Curated OER
Constructing Midsegments of Triangles
Learners construct midsegments. In this geometry instructional activity, students make conjectures and apply properties of triangles to solve problems. They complete an activity on the computer.
Curated OER
Classifying Triangles
In this classifying triangles worksheet, 10th graders solve 9 various problems that classify triangles into categories. First, they refer to the figure shown of an isosceles triangle with two line parallel. Then, students name the sides,...
Illustrative Mathematics
Are They Similar?
Learners separate things that just appear similar from those that are actually similar. A diagram of triangles is given, and then a variety of geometric characteristics changed and the similarity of the triangles analyzed. Because the...
Virginia Department of Education
High School Mathematics Geometry Vocabulary Word Wall Cards
Having a good working knowledge of math vocabulary is especially important for geometry learners. Here are 119 pages worth of wonderfully constructed definitions, constructions, formulas, properties, theorems, and postulates. This is a...
Curated OER
Marshmallow Geometry
In this three-dimensional shapes geometry lesson, learners identify geometric solids and name their properties. They define "face," "edge," and "vertex," and construct geometric solids using marshmallows as vertices and toothpicks as edges.
Virginia Department of Education
Middle School Mathematics Vocabulary Word Wall Cards
Having a good working knowledge of math vocabulary is so important for learners as they progress through different levels of mathematical learning. Here is 125 pages worth of wonderfully constructed vocabulary and concept review cards....