EngageNY
Triangle Congruency Proofs (part 1)
Can they put it all together? Ninth graders apply what they know about proofs and triangle congruence to complete these proofs. These proofs go beyond the basic triangle congruence proofs and use various properties, theorems, and...
Curated OER
Geometry - Angles Overview
Learners address 14 questions that include naming all pairs of opposite and supplementary angles for sets of intersecting lines and then, finding the measure of the unknown angle. They determine the measure of the angle that is...
Curated OER
Angles
Here is a well-designed presentation on different types of angles for your young geometers. In it, learners view slides that clearly illustrate what these angles are, and how they are formed. Excellent practice when introducing these...
CK-12 Foundation
Unit Circle: Medieval Castle Defense
Who needs a plan — let trigonometry protect you! Pupils determine the angle of an approaching enemy to a village wall. The scholars determine the exact value of trigonometric functions for the angle. Class members use trigonometry to...
EngageNY
Ptolemy's Theorem
Everyone's heard of Pythagoras, but who's Ptolemy? Learners test Ptolemy's Theorem using a specific cyclic quadrilateral and a ruler in the 22nd installment of a 23-part module. They then work through a proof of the theorem.
EngageNY
Unknown Angle Problems with Inscribed Angles in Circles
We know theorems about circles—now what? Class members prove a theorem, with half the class taking the case where a point is inside the circle and half the class taking the case where a point is outside the circle. The activity then...
Curated OER
Similarity and Dilations - Discover Properties of Similar Figures
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...
EngageNY
Sequencing Rotations
Discover the result of a sequence of rotations about different centers. Pupils perform rotations to examine the patterns. They also describe the sequence of rotations that performed to reach a desired result in the ninth installment in a...
Concord Consortium
Short Pappus
It's all Greek to me. Scholars work a task that Greeks first formulated for an ancient math challenge. Provided with an angle and a point inside the angle, scholars develop conjectures about what is true about the shortest line segment...
Curated OER
Exploring and Using Shapes to Make a Dance
Second graders use their bodies to create various shapes to make a dance when given various music and beats. In this shapes and dance lesson plan, 2nd graders create lines, curves, twists, and angles with their bodies.
101 Questions
Snail's Pace
Time doesn't fly when you're watching a snail cross a sidewalk. Combining the concepts of the Pythagorean Theorem and the distance, rate, and time formula, learners determine how long it takes a snail to go from one corner of a sidewalk...
Curated OER
City Streets: A Fold-up of a Street Lined with Buildings
After walking in a nearby neighborhood, have your class create this amazing city street pop-up. They study the facades of the buildings they see, focusing on geometric line, shape, and architecture. They then draw, cut, and create a city...
Concord Consortium
Rectangle Space
Take a coordinated look at rectangles. The task asks pupils to plot the length and width of created triangles in the coordinate plane. Using their plots, scholars respond to questions about rectangles and their associated points on the...
Curated OER
Triangles
In this triangles instructional activity, 10th graders solve 3 extensive informal geometry problems that involve triangles. First, they sketch a triangle, selecting 3 of the sides and constructing 3 midpoints. Students then draw each of...
Curated OER
Section 6.1-6.2 Precalculus: Trigonometry
In this trigonometry worksheet, learners solve 15 triangle problems. Students use the law of sines and law of cosines to find the missing angles and side lengths of a triangles.
Curated OER
Exploring Polygons and The Greedy Triangle
Excellent lesson plan! Anne Linehane's geometry story, The Greedy Triangle, offers an opportunity to practice forming various types of polygons with your learners. Using elastic bands (or Chinese jump ropes),...
Dick Blick Art Materials
Start with a Circle...
The Golden Ratio. The Divine Proportion. Yup. It's math and art blended into one colorful activity. Young artists combine colored tissue paper circles and parts of circles to create geometric patterns. As a bonus, kids get to figure out...
Curated OER
Find Missing Angles of Triangles
In this triangles activity, students find the missing angles of a set of 4 triangles. Answers are included on page 2.
Curated OER
Using Slope Angles
In this geometry instructional activity, 10th graders use right triangle trigonometry to solve problems involving angle of elevation or depression. The one page instructional activity contains eleven problems. Answers are not...
Curated OER
Measuring Angles in Triangles
For this measuring angles in triangles worksheet, 10th graders solve 12 different measurement problems with angles within triangles. First, they find the value of x in each triangle given the angle measurements. Then, students find the...
Curated OER
Triangle Inequalities
For this triangle inequalities worksheet, 10th graders solve 10 different problems that include various types of triangles. First, they determine which side is the longest side of a triangle with given the exterior angle measurement....
Curated OER
Interior and Exterior Angles of Polygons
Students identify interior and exterior angles of polygons. In this geometry lesson, students add interior and exterior angles of polygons. They use angle theorems to solve the problems.
Curated OER
Law of Cosines
In this Law of Cosines worksheet, 10th graders solve 10 different problems related to applying the Laws of Cosine. First, they determine the length of a side rounded to the nearest integer. Then, students determine the largest angle of a...
University of Utah
Geometry: Angles, Triangles, and Distance
The Pythagorean Theorem is a staple of middle school geometry. Scholars first investigate angle relationships, both in triangles and in parallel lines with a transversal, before proving and applying the Pythagorean Theorem.