Curated OER
Symmetries of a Quadrilateral I
Learners examine the properties of quadrilaterals from the point of view of rigid motion. Different types of quadrilaterals are characterized by their symmetries, so learners explore the symmetries of a described quadrilateral to...
Curated OER
Symmetries of a Quadrilateral II
Learners investigate the symmetries of a convex quadrilateral in a collaborative activity. Rigid motion and complements are explored as learners analyze different cases of reflections across a line.
Curated OER
Tile Patterns I: Octagons and Squares
This can be used as a critical thinking exercise in congruence or as a teaching tool when first introducing the concept. Four octagons are arranged in such a way that a square is formed in the middle. With this information, geometry...
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...
Illustrative Mathematics
What is a Trapezoid? (Part 1)
Challenge your class to construct a definition for trapezoids. Looking at four examples and four non-examples, students individually create definitions and use them to classify an unknown shape. Allow for small group and whole-class...
Illustrative Mathematics
Grandfather Tang's Story
It's amazing the complex figures that can be made using only a few simple shapes. Following a class reading of the children's book Grandfather Tang's Story by Ann Tompert, young mathematicians use sets of tangrams to create models...
Illustrative Mathematics
Counting Squares
Challenge young mathematicians' understanding of squares with this geometry puzzle. The task is simple, identify as many squares as possible in a 3x3 array. Allow learners to work independently or in pairs as they search for squares,...
Illustrative Mathematics
Alike or Different Game
How are a circle and triangle alike? How are they different? These are the types of questions children will answer while playing this fun geometry game. Including a variety of conventional and unconventional shapes, this activity allows...
Illustrative Mathematics
All vs. Only Some
All shapes have certain defining attributes that set them apart from others. In order to understand this, young mathematicians look at examples and non-examples of triangles, rectangles, and squares, working as a whole class to create...
Illustrative Mathematics
Overlapping Rectangle
Challenge young mathematicians' ability to compose and decompose shapes with this fun geometry puzzle. The goal is simple, locate all of the rectangles shown in a picture of three overlapping rectangles. Perform this activity as a whole...
Illustrative Mathematics
Finding an Unknown Angle
Teach your class how to apply their knowledge of geometry as they explore the unknown. In order to find an unknown angle, students must understand that rectangles have four interior right angles, that right angles have 90 degrees, and...
Curated OER
Is This a Rectangle?
How do you show that something is a rectangle? This activity starts with four coordinate points and asks young geometers to explain whether they create a rectangle. Knowledge from both geometry and algebra come into play here, as well...
Illustrative Mathematics
Sum of Angles in a Polygon
How can learners use algebra to solve a geometry problem? Help learners create an equation that shows the relationship between the number of sides of a polygon and the sum of the interior angles. Young scholars are asked to divide the...
Education Development Center
Finding Parallelogram Vertices
Four is the perfect number—if you're talking about parallelograms. Scholars determine a possible fourth vertex of a parallelogram in the coordinate plane given the coordinates of three vertices. They read a conversation...
Texas Instruments
Texas Instruments: Cyclic Quadrilaterals
Students construct cyclic quadrilaterals and investigate their properties. They determine which quadrilaterals from the quadrilateral hierarchy are cyclic.
Los Angeles County Office of Education
Los Angeles County Office of Education: Quadrilateral Quest
Use your knowledge of properties of quadrilaterals to correctly match quadrilaterals.
Texas Instruments
Texas Instruments: Investigating Segments in a Quadrilateral
In this activity, students use the tools of Cabri Jr to test their knowledge of geometry. They investigate the properties of the shape formed by connecting the midpoints of adjacent sides of a quadrilateral.
CK-12 Foundation
Ck 12: Inscribed Quadrilaterals in Circles
[Free Registration/Login Required] Students will explore quadrilaterals inscribed in circles with this interactive activity. Click 'Challenge Me' to answer a practice question.
CK-12 Foundation
Ck 12: Quadrilateral Classification
[Free Registration/Login Required] Students will move the vertices of the quadrilateral to form the congruent quadrilateral. Click learn more to watch a video and click challenge me to answer a practice question.
CK-12 Foundation
Ck 12: Quadrilateral Classification
[Free Registration/Login Required] Students move the vertices to the given ordered pairs to determine the type of quadrilateral. Click learn more to watch a video and click challenge me to answer a practice question.
CK-12 Foundation
Ck 12: Quadrilaterals That Are Parallelograms
[Free Registration/Login Required] Students will move the interactice quadrilateral to determine which quads are parallelograms. Click learn more to watch a video and click challenge me to answer a practice question.
Maths Challenge
Maths challenge.net: Quadrilateral Parallelogram
A "three star geometry problem" requiring knowledge of how to complete geometric proofs and some prior math knowledge. This problem asks to prove that the mid points of any quadrilateral form a parallelogram.
National Council of Teachers of Mathematics
The Math Forum: Problems Library Geometry Triangles
This site contains a wealth of problems that deal with the basic definitions of medians, altitudes, angle bisectors, and perpendicular bisectors or the defining characteristics of the different types of triangles. There are also...
Texas Instruments
Texas Instruments: Perimeters, Areas, and Slopes Oh, My!
In this activity, students create geometric figures, and use analytic and coordinate geometry to investigate their attributes. They go through the process of proving that a quadrilateral is a parallelogram.