Curated OER
Why Doesn't SSA Work?
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.
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...
Mt. San Antonio Collage
Properties of a Parallelogram
More than just a activity, the resource provides a thorough guide to navigate through the land of parallelograms. Filled with definitions and theorems, the resource supports learners through problems such as proofs and finding missing...
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....
Curated OER
Why Does SAS Work?
Your geometry learners are guided by questions that help them use the language of reflections to explain the Side-Angle-Side congruence between two triangles in this collaborative task. Given a sample solution, declaring the triangles...
Curated OER
Geometry and Measurement Pre-Test
Use this comprehensive pre-instruction assessment tool to focus your teaching where your class needs it most. Multiple choice questions assess your budding geometers' conceptual and vocabulary knowledge, but they do not solve any...
Curated OER
Finding the Area of an Equilateral Triangle
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...
EngageNY
Circles, Chords, Diameters, and Their Relationships
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...
Virginia Department of Education
Similar Triangles
Pupils work in pairs to investigate what it takes to prove that two triangles are similar. They work through various shortcuts to find which are enough to show a similarity relationship between the triangles. Small groups work with the...
Curated OER
Can You Name That Shape?
Learners use materials to build, investigate, and draw two-dimensional shapes (polygons). They combine the shapes they have built and draw from the pile to begin a round-robin activity to name and determine the attributes of a selection...
Illustrative Mathematics
Is This a Parallelogram?
If both pairs of opposite sides of a quadrilateral are congruent, is the quadrilateral a parallelogram? This task asks learners to determine the answer and to support their answer with a proof. The resource includes a commentary for...
Houghton Mifflin Harcourt
Developing the Concept: Triangles and Quadrilaterals
Exact narrative and examples make this lesson on polygons easy to implement. Through it, your class will learn how to use a protractor and ruler to construct triangles and quadrilaterals according to your directions. Your class will be...
Curated OER
Tangrams
Learners construct tangram pieces. Then they make observations and explore patterns with the pieces.
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
Plain Figures and Measuring Figures
Students investigate basic geometric concepts. In this geometry lesson, students explore solids through measuring and modeling. This assignment models the importance of understanding concrete objects in geometry.
Curated OER
Properties of Parallelograms
High schoolers discover properties of parallelograms as they construct a parallelogram using Cabri Jr. They will measure angles and side lengths of their construction and determine the relationship between the diagonals of a...
Curated OER
Why do Stars Rise in the East?
In this stars rise in the east worksheet, students use geometry to show how the Earth rotates from west to east and why celestial bodies appear to rise in the east and set in the west. Students draw a figure and label given points in...
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...
Texas Instruments
Investigating Segments in a Quadrilateral
Investigate the properties of the shape formed by connecting the midpoints of adjacent sides of a quadrilateral. In this properties of the shape formed by connecting the midpoints of adjacent sides of a quadrilateral lesson, high...
Key Curriculum Press
Properties of Special Parallelograms
Rhombuses, rectangles and squares are have special properties. In this lesson, young geometers investigate and make conjectures about diagonals, angles, and parallel lines of parallelograms.
Curated OER
Geoboard Activity
In this geometry worksheet, 10th graders use geoboards or the grid representation of a geoboard to construct the indicated geometric figure. The three page worksheet contains twenty-seven questions. Answers are not included.
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...
Curated OER
Circumscribed Polygons
Students investigate polygons and construct ferris wheels. In this geometry lesson plan, students create a circle and differentiate properties of circles and polygons. They compare the relationship between angles and circumscribed polygons.
Curated OER
Studying Special Segments in Triangles
Learners investigate special segments in triangles. In this geometry lesson, students graph, compare, estimate and predict findings based on their data. They differentiate between similarity and congruence of triangles.