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
Writing and Solving Linear Equations
Incorporate geometry into the solving linear equations lesson. Pupils use their knowledge of geometry to write linear equations which reinforces geometry measurement concepts while at the same time providing a familiar context for...
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.
Radford University
Streets of Stephens City
Who has the best street smarts? An educational lesson has future mathematicians analyze street maps and measure angles on the map to determine if streets are parallel. They also consider safety issues at different types of intersections.
Flipped Math
Proving Lines Parallel
Show it can all be proved. Scholars learn the converses of the properties of parallel lines. Using the converses, pupils determine which lines are parallel based on angle measurements and practice using a flow proof to show that two...
Flipped Math
Unit Circle and Radians
Measure angles is easy as pi. Pupils review special right triangles to find exact values for trigonometric functions. Scholars learn about radians and how they connect to measurements in degrees. They find exact and approximate values of...
Flipped Math
Tangents to Circles
Touch a circle once. Individuals watch a video and learn two theorems related to tangents and circles. The pupils then apply the theorems to find missing angle measures and lengths in figures. At the end, they practice their skills on...
EngageNY
Addition and Subtraction Formulas 1
Show budding mathematicans how to find the sine of pi over 12. The third lesson in a series of 16 introduces the addition and subtraction formulas for trigonometric functions. Class members derive the formulas using the distance formula...
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.
Willow Tree
Ratios and Proportions with Congruent and Similar Polygons
Investigate how similar and congruent figures compare. Learners understand congruent figures have congruent sides and angles, but similar figures only have congruent angles — their sides are proportional. After learning the...
Mathematics Vision Project
Geometric Figures
Logical thinking is at the forefront of this jam-packed lesson, with young mathematicians not only investigating geometric concepts but also how they "know what they know". Through each activity and worksheet, learners wrestle with...
Scholastic
Study Jams! Area of a Triangle
Even though there is a wide variety of different triangles in the world, knowing a single equation allows us to find the area of each and every one of them. Follow along with this step-by-step presentation as Zoe clearly models how to...
CK-12 Foundation
Length of an Arc: Pi Hour
What time is it when the arc length is pi? An interactive displays the measure of the angle created between the hour and minute hand of a clock. Pupils can set the clock to different hours and calculate the arc length based upon the radius.
Flipped Math
Intro to Trigonometry
Expand trigonometric ratios beyond right triangles. Pupils start with a review of trigonometric ratios and then take a look at angles in standard position to determine their measurements. Scholars discover how to find coterminal angles...
Flipped Math
Properties of Parallel Lines
Work within a parallel universe. Scholars learn about the relationships of angles when two parallel lines are intersected by a transversal. They see how to find the measurements of all eight angles by knowing the measure of one angle....
Scholastic
Study Jams! Congruent Figures
There is more to congruency than just looking similar. Learn the difference and calculate the matching angles and sides to prove the congruence between figures. Lesson has step-by-step slides and follows with an assessment.
CK-12 Foundation
Pythagorean Theorem for Solving Right Triangles: Solving the Triangle
Observe the change in the trigonometric ratios as angles vary. An interactive provides the values of trigonometric ratios for both acute angles in a right triangle. Pupils create a right triangle to match given criteria and find the...
PBS
Accessible Shapes
All the 2-D and 3-D measurement work you need is in one location. Divided into three sections, the geometry lesson plans consist of visualization of three dimensions, classifying geometric figures, and finding surface area and volume....
Flipped Math
Inverse Trig Ratios
Put trigonometric ratios into inverse. Scholars learn how to find an unknown angle in a right triangle by using inverse trigonometric ratios. The pupils understand how the inverses undo a trigonometric ratio to provide the angle measure....
Las Cumbres Observatory
The Cosmic Distance Ladder: Parallax
Scientists don't have a ruler long enough to measure to the stars, so they rely on math. Scholars learn to calculate the distance from Earth to a star using the parallax method. They use angle measures from different perspectives to...
Virginia Department of Education
Constructions
Pupils learn the steps for basic constructions using a straightedge, a compass, and a pencil. Pairs develop the skills to copy a segment and an angle, bisect a segment and an angle, and construct parallel and perpendicular lines.
Curated OER
Transformations in the Coordinate Plane
Your learners connect the new concepts of transformations in the coordinate plane to their previous knowledge using the solid vocabulary development in this unit. Like a foreign language, mathematics has its own set of vocabulary terms...
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....
EngageNY
More About Similar Triangles
Determine whether two triangles are similar. The lesson presents opportunities for pupils to find the criterion needed to show that two triangles are similar. Scholars use the definition of similarity to find any missing side...
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