Mt. San Antonio Collage
Isosceles Triangles and Special Line Segments
Under which conditions can a triangle be classified as isosceles? High schoolers practice identifying isosceles triangles and special line segments, including angle bisectors, medians of triangles, and perpendicular bisectors of sides of...
Bowland
Rods and Triangles
Scholars explore triangles with rods of different lengths. Using rods of 2, 4, 6, 8, and 10 cm class members build as many different types of triangles as they can. They also describe properties of these triangles and determine...
Inside Mathematics
Circles in Triangles
Challenge the class with inscribed circles in triangles. The assessment task requests class members use their knowledge of circles and right triangles to prove two triangles are congruent. They go on to utilize their knowledge of...
Concord Consortium
Triangles: Angle Space
Three angles in a triangle, three-dimensional space, it all seems connected somehow. Given several different triangles, pupils use the three angles of the triangle as coordinates to plot points in three-dimensional space. They explore...
EngageNY
Congruence Criteria for Triangles—ASA and SSS
How do you know if a pair of triangles are congruent? Use the lesson to help class members become comfortable identifying the congruence criteria. They begin with an exploration of ASA and SSS criteria through transformations and...
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...
Education Development Center
Similar Triangles
Model geometric concepts through a hands-on approach. Learners apply similar triangle relationships to solve for an unknown side length. Before they find the solution, they describe the transformation to help identify corresponding sides.
Mathematics Assessment Project
Inscribing and Circumscribing Right Triangles
High schoolers attempt an assessment task requiring them to find the radii of inscribed and circumscribed circles of a right triangle with given dimensions. They then evaluate provided sample responses to consider how to improve their...
Curated OER
Identifying Triangles
In this triangles practice worksheet, students respond to 4 questions that require them to identify the pictured triangles as acute, right, obtuse, scalene, isosceles, or equilateral triangles.
Curated OER
Identify triangles
Learners explore triangles. In this geometry lesson plan, students will create note cards with pictorial depictions of right, acute,obtuse, scalene, isosceles, equilateral and equiangular triangles. Learners will verbally describe each...
Curated OER
Identifying Triangles
Sixth graders identify and define a variety of triangles. In this identification of triangles lesson, 6th graders draw examples of each triangle on a whiteboard, then complete a worksheet.
Curated OER
A Triangle Expansion
Students review the foil method used to multiply two binomials. For this lesson on evaluating algebraic expressions, students are able to identify the coefficient in an algebraic expression, "act out" the foil method of multiplying...
CK-12 Foundation
Possible Triangles with Side-Side-Angle
It's not often that math allows for multiple answers. Young mathematicians identify possible numbers of triangles when given two sides and a non-included angle. An interactive helps with this investigation.
Curated OER
Identifying Triangles
In this geometry worksheet, 10th graders identify a triangle as right, acute, or obtuse and identify the parts of a right triangle in a drop and drag game format. The one page interactive worksheet contains eight matching questions and...
Curated OER
Triangles
In this triangle activity, students identify triangles according to the characteristics of their sides. Students identify scalene, isosceles, equilateral and right triangles. Eleven triangle problems are provided in this one-page...
Curated OER
The Truth About Triangles And Proofs
Students engage in a lesson that is about the classification of triangles and the mathematical proofs involved in working with them. They work on a variety of problems that are created by the teacher with the focus upon the importance of...
Curated OER
Basic Right Triangles
Elementary schoolers examine the attributes of triangles. In this triangle instructional activity, learners compare regular triangles and right triangles. They explore vertices and angles and investigate obtuse and acute angles. Pupils...
EngageNY
Incredibly Useful Ratios
Start the exploration of trigonometry off right! Pupils build on their understanding of similarity in this lesson plan that introduces the three trigonometric ratios. They first learn to identify opposite and adjacent...
CK-12 Foundation
Trigonometric Functions and Angles of Rotation: The Triangle in the Circle
Go around the unit circle and create triangles. Pupils move a point around the unit circles to visualize the triangle associated with the angle in standard position. The three main trigonometric functions are defined in terms of the legs...
Curated OER
Corresponding Parts of Congruent Triangles
Students identify different parts of a triangle. In this geometry lesson plan, students differentiate between similar and congruent triangles. They use the navigator to crate a visual of the different parts of a triangle.
Curated OER
How many isosceles triangles can you find?
Seventh graders recognize the characteristics of isosceles triangles. In this isosceles triangle instructional activity, 7th graders use geoboards to create isosceles triangles. Students record results and explain why they have an...
Curated OER
Special Segments of Triangles Jigsaw Activity
Young scholars identify the special segments of triangles, the median, angle bisector, altitude, and perpendicular bisectors.
Curated OER
30-60-90 Right Triangles in Cabri Jr.
Young mathematicians draw and label right triangles using Cabri Jr. technology. They create other special right triangles and identify the length of the hypotenuse and each leg. High schoolers explore the ratios to determine how the...
Curated OER
Triangle Sum Theorem
Teach your class how to solve problems using the triangle sum theorem. In this geometry instructional activity, students identify the missing angles in a triangle using the sum theorem. They graph triangles on the TI and moves the sides...