CK-12 Foundation
Identifying Sets of Pythagorean Triples: Matching Problem
What sets of whole numbers make up the measures of side lengths in right triangles? Pupils use an interactive triangle to learn about Pythagorean triples. Individuals find missing values in triples and learn more about Pythagorean...
Illustrative Mathematics
Finding Areas of Polygons, Variation 1
An exercise in finding the area of polygons by decomposing into triangles and composing into rectangles is the focus of this resource. Make several copies of the worksheet for each participant. Ask learners to use colored pencils to...
National Woman's History Museum
The Triangle Shirtwaist Fire
On March 25, 1911, 146 garment workers died in the Triangle Shirtwaist Factory fire. Class members use primary source documents to research the tragedy and how it lead to the creation of labor unions and new labor laws. As an exit...
CK-12 Foundation
Identify Accurate Drawings of Triangles: Law of Cosines
Drawing triangles is easy, even if you have to calculate the exact length of its sides. Scholars use the Law of Cosines to find missing sides of triangles. An interactive helps them check their answers.
CK-12 Foundation
Angle-Side-Angle Triangles: Caution Tape
Don't lose your marbles. Scholars use an interactive to create a triangle that closes off a portion of a sidewalk with loose marbles. The Law of Sines helps them find the side measures of such a triangle.
Centers for Disease Control and Prevention
Understanding the Epidemiologic Triangle through Infectious Disease
Introduce infectious diseases and the epidemiologic triangle. A helpful resource describes the agent, host, and environment from the three vertices as well as the time factor, which is in the middle. Scholars complete a simple...
University of Wisconsin
Why Did the Triangle Fire Occur?
An investigation of the 1911 New York City Triangle Shirtwaist Factory fire leads class members to examine primary and secondary source materials related to the event and apply what they learn about the working conditions at the time to...
Mathematics Vision Project
Similarity and Right Triangle Trigonometry
Starting with similar triangles and dilation factors, this unit quickly and thoroughly progresses into the world of right triangle features and trigonometric relationships. Presented in easy-to-attack modules with copious application...
EngageNY
Proof of the Pythagorean Theorem
What does similarity have to do with the Pythagorean Theorem? The activity steps through the proof of the Pythagorean Theorem by using similar triangles. Next, the teacher leads a discussion of the proof and follows it by an animated...
EngageNY
The Converse of the Pythagorean Theorem
Is it a right triangle or not? Introduce scholars to the converse of the Pythagorean Theorem with a lesson that also provides a proof by contradiction of the converse. Pupils use the converse to determine whether triangles with given...
Arizona Department of Education
Area and Perimeter of Regular and Irregular Polygons
Extend young mathematicians' understanding of area with a geometry lesson on trapezoids. Building on their prior knowledge of rectangles and triangles, students learn how to calculate the area of trapezoids and other irregular...
EngageNY
Modeling Using Similarity
How do you find the lengths of items that cannot be directly measured? The 13th installment in a series of 16 has pupils use the similarity content learned in an earlier resource to solve real-world problems. Class members determine...
Illustrative Mathematics
Bank Shot
Young geometers become pool sharks in this analysis of the angles and lengths of a trick shot. By using angles of incidence and reflection to develop similar triangles, learners plan the exact placement of balls to make the shot....
Flipped Math
Reference Triangles
It is all about where the side is located. Pupils use their knowledge of angles in standard position to find reference angles. They use the Pythagorean Theorem to find lengths along a terminal side of an angle to determine the exact...
Center for History Education
The Triangle Shirtwaist Factory Fire: Is Anyone to be Punished for This?
The stories of bodies falling to the pavement and girls dying in their seats echo to the present day. The New York City Triangle Shirtwaist Factory fire—which killed 147 people, mostly young women and girls—galvanized the labor movement...
Illustrative Mathematics
Applying the Pythagorean Theorem in a Mathematical Context
Participants who use this resource will apply the Pythagorean Theorem to show whether or not the shaded triangle inscribed in a rectangle is a right triangle. Once all of the sides on the shaded triangle are found, it is important that...
Music Fun
Instruments to Trace Color and Label
Handbells and castanets. Triangles and timpani. Trumpets and trombones. As part of their study of instruments, young musicians label, trace and color the parts of seven instruments. Also included in the resource packet are tracing...
West Contra Costa Unified School District
Law of Sines
One must obey the sine laws. A lesson plan introduces and derives the Law of Sines for non-right triangles. With examples that use the Law of Sines to determine unknown measures in triangles, the lesson plan checks to see if the Law of...
Utah Education Network (UEN)
Geometric Figures and Scale Drawings
Scale up your lessons on geometry and ask learners to investigate conditions on triangles, scale drawings, the area and circumference of circles, and angle relationships. The resource includes activities and a homework assignment.
CK-12 Foundation
Angles of Elevation and Depression: Fly-By Calibration
Determine the distance between two trees from afar. Pupils use an interactive resource to create two right triangles using trees and a plane. They determine the horizontal legs of each triangle to find the distance between the two trees.
Mathed Up!
Loci and Constructions
A General Certificate of Secondary Education math review has class members make basic constructions. Using a protractor and a ruler along with a compass, pupils develop drawings of triangles with given measurements. Scholars use their...
CK-12 Foundation
Area Between Curves: Income and Expenses
Use the area of polygons to calculate the area between curves. Pupils calculate areas under income and expense curves by filling the space with squares and right triangles. Using that information, they determine the profit related to the...
Mathed Up!
Pythagoras' Theorem
Use a right method to find a distance. Given a right triangle, class members find the length of one side given the measurement of the other two sides—the missing side may or may not be the hypotenuse. A video reminds the pupils how to...
Corbett Maths
Hexagon Inscribed Within a Circle
Mark off the length of the radius around the circle. Using a compass, the presenter shows how to construct a regular hexagon in a circle. Pupils see how triangles formed in the hexagon are equilateral, allowing for the construction to...
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