Illustrative Mathematics
Placing a Fire Hydrant
Triangle centers and the segments that create them easily become an exercise in memorization, without the help of engaging applications like this instructional activity. Here the class investigates the measure of center that is...
EngageNY
Thales’ Theorem
Isn't paper pushing supposed to be boring? Learners attempt a paper-pushing puzzle to develop ideas about angles inscribed on a diameter of a circle. Learners then formalize Thales' theorem and use geometric properties to develop a proof...
Curated OER
Indirect Euclidean Proofs
In this Euclidean proofs worksheet, 10th graders solve 10 different problems that include completing indirect Euclidean proofs. First, they write a statement for each of the reasons listed on the sheet of proofs. Then, students solve the...
Curated OER
Indirect Euclidean Proofs
In this indirect Euclidean proof worksheet, students write statements supporting the reasons for a given proof. This one-page worksheet contains ten problems.
Curated OER
Quiz: Beginning Congruent Triangle Proofs
In this congruent triangle proof learning exercise, students write theorems to prove the congruence of given triangles. This one-page learning exercise contains three given polygons to prove congruence.
Texas Instraments
Angles in Circles
Teach your learners how to investigate the relationship between a central angle and an inscribed angle which subtend the same arc of a circle. The dynamic nature of Cabri Jr. provides opportunity for conjecture and verification.
EngageNY
Proving the Area of a Disk
Using a similar process from the first lesson in the series of finding area approximations, a measurement resource develops the proof of the area of a circle. The problem set contains a derivation of the proof of the circumference...
EngageNY
Construct an Equilateral Triangle (part 2)
Triangles, triangles, and more triangles! In this second installment of a 36-part series, your young mathematicians explore two increasingly challenging constructions, requiring them to develop a way to construct three triangles that...
Curated OER
Tangents to a Circle
Students construct tangent lines. In this geometry lesson plan, students identify the point of tangency, secant and tangent lines. They graph the lines on the Ti and make observations.
EngageNY
Law of Sines
Prove the Law of Sines two ways. The ninth segment in a series of 16 introduces the Law of Sines to help the class find lengths of sides in oblique triangles. Pupils develop a proof of the Law of Sines by drawing an altitude and a second...
Curated OER
Preparation and Transition to Two-Column Proofs
Students investigate proofs used to solve geometric problems. For this geometry lesson, students read about the history behind early geometry and learn how to write proofs correctly using two columns. The define terminology valuable to...
Curated OER
History / Introduction of Pythagorean Theorem
Learners explore Pythagoras and the history behind his theorem. They work together to solve a proof that is embedded in the lesson.
Curated OER
Inscribed Angles
In this inscribed angles worksheet, 10th graders solve 13 various types of problems related to inscribed angles in geometry. First, they identify a circle illustrated and each arc of the circle. They, students find the measure of each...
Curated OER
Around the World With Geometry
Students identify shapes, create shapes, and make a pyramid, a drum, and a sail using their shapes. In this shapes lesson plan, students also identify plane and space shapes.
Curated OER
Euclidean Proofs involving Triangles and Circles (Congruency Proofs)
In this geometry worksheet, 10th graders focus on Euclidean proofs involving triangles and circles. The eight page worksheet contains eight proofs. Solutions are not provided.
Shodor Education Foundation
Cross Sections
Use this activity on cross-sections of three-dimensional shapes in your math class to work on algebra or geometry Common Core standards. The lesson includes a list of relevent terminology, and a step-by-step process to illustrate the...
Curated OER
DEAD MAN'S CURVE
Ninth graders, after being given a unique scenario and a task sheet on Dead Man's Curve, calculate and explain the force needed to keep a car on a curve using a set of formulas and a geometric property of circles. They utilize and create...
EngageNY
Arcs and Chords
You've investigated relationships between chords, radii, and diameters—now it's time for arcs. Learners investigate relationships between arcs and chords. Learners then prove that congruent chords have congruent arcs, congruent arcs have...
Curated OER
Identify the Shape
10 this geometry worksheet, students identify the different angles created by polygons and name the shape created based on the number of sides. There is an answer key.
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.
Curated OER
Investigating AAS
Young scholars investigate the theorems of ASA, AAS, AAA and ASA. In this geometry lesson, students 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 two...
Curated OER
Pape's Theorems
In this math worksheet, students find the length of the side of a regular hexagon whose area is numerically equal to its perimeter.
Curated OER
Line and Shape Game
Learners play the "space-breaker" game, in which they are required to create a picture using shapes or lines called out to them) to reinforce the concept of geometric shape and line.
Curated OER
Line and Shape Game
Students create a picture of an actual scene or overlap the called out lines or shapes into a space-breaker. If someone calls out a line or shape a student had not planned to use in the art, they have to figure out some way to use it...