Curated OER
Tessellations
Seventh graders investigate geometric shapes using tessellations. In this geometry lesson, 7th graders practice tessellations using different shapes. They create different designs using tessellations.
Curated OER
Pattern Block Polygons
Sixth graders create polygons. In this shapes activity, 6th graders explore prefixes such as oct, tri, quad, pent, etc. and share their findings. Students use pattern blocks to create two different polygons and label them.
Curated OER
Understanding Fundamental Trigonometric Identities
Students are introduced to the basic trigonometric identities. Using a diagram, they discover why the parts of the unit circle as named as they are and use equations to finalize the Pythagorean trigonometric identities. They also review...
Curated OER
The Pythagorean Theorem, the Distance Formula, and Slope
Learners explore the concept of the Pythagorean Theorem. In this Pythagorean Theorem activity, students derive the distance formula and slope of a line from the Pythagorean Theorem.
Curated OER
SAT Practice Test
In this secondary mathematics worksheet, students assess their readiness for the SAT test. The one page, interactive worksheet contains ten problems. Solutions are not provided.
Curated OER
Symmetry and Tessellations
Sixth graders investigate tessellations and their origins. Students trace triangles to form a tessellation. They measure the angle of equilateral triangles. Students locate the line of symmetry, they create geometric squares,...
Curated OER
Proposed Problems
In this math worksheet, students find the solutions to the problems that involve solving equations with and without rational expressions.
Texas Instruments
Texas Instruments: Sum of Interior Angles in a Triangle With Cabri Jr.
Students will discover the sum of the interior angles in a triangle using the Cabri Jr. Application.
Mangahigh
Mangahigh: Shape: Proof of the Sum of the Angles in a Triangle
Determine that all angles in a triangle equal 180 degrees.
Illustrative Mathematics
Illustrative Mathematics: A ced.a.1: Sum of Angles in a Polygon
This problem provides students with an opportunity to discover algebraic structure in a geometric context. They will divide up polygons into triangles. The will use the sum of the angles of 180 degrees for each triangle. Aligns with...
Walter Fendt
Walter Fendt: Sum of Angles in a Triangle
A short interactive activity to show that the sum of the angles of a triangle is 180 degrees.
Texas Instruments
Texas Instruments: Measuring Angles in a Triangle
In this activity, students learn about the sum of the angles in a triangle. They understand triangles and their interior angles.
Government of Alberta
Learn Alberta: Math Interactives: Exploring Angles Within a Triangle
This multimedia Learn Alberta math resource looks at angles of a triangle in the context of building bikes and choosing bike sizes. The accompanying interactive component lets students explore build different sized triangles while...
Calculator Soup
Calculator Soup: Triangle Theorems Calculator
Each calculation option has sub-bullets that list the sequence of methods used in this calculator to solve for unknown angle and side values including Sum of Angles in a Triangle, Law of Sines, and Law of Cosines.
Texas Instruments
Texas Instruments: Extension: Parallel Lines and the Sum of the Angles
Students construct a line parallel to the base of a triangle and measure the angles formed. They use the construction to prove that the sum of the measures of the interior angles of a triangle is 180 degrees.
CK-12 Foundation
Ck 12: Geometry: Exterior Angles Theorems
[Free Registration/Login may be required to access all resource tools.] This concept teaches students the sum of exterior angles for any polygon and the relationship between exterior angles and remote interior angles in a triangle....
Illustrative Mathematics
Illustrative Mathematics: 8.g.a Triangle's Interior Angles
In this task, 8th graders are presented with a drawing of two parallel lines with a triangle touching them at all three of its vertices. They are asked to prove that the sum of the triangles' angles equals 180 degrees. Aligns with 8.G.A.5.
Texas Instruments
Texas Instruments: Angles of a Triangle
In this activity, students investigate the sum of the measures of the interior angles of a triangle. They will explore interior angles, and their relationship with the exterior angles of a triangle.
Texas Instruments
Texas Instruments: Angle Sum in Triangles Proof: Rotation and a Parallel Line
This investigation uses Cabri Jr. and a cleaver rotation of a triangle to "prove" that the angles in a triangle add up to 180. This could be used to reinforce triangles and paralled lines as well as introduce the concept of rotating an...
Illustrative Mathematics
Illustrative Mathematics: 8.g Find the Angle
In this task, 8th graders have to reason with angles and angle measurements, including the sum of the angles in a triangle, to deduce information from a picture. Includes a GeoGebra worksheet that the teacher can use for demonstration...
Khan Academy
Khan Academy: Find Angles in Triangles
Find missing angle measures using the properties of triangles. Students receive immediate feedback and have the opportunity to try questions repeatedly, watch a video, or receive hints.
Math Is Fun
Math Is Fun: Interior Angles of Polygons
Learn what an interior angle of a polygon is and how you can calculate their value in triangles, quadrilaterals, and pentagons. Includes a chart that overviews the "general rule" for determining the sum of internal angles in any polygon...
Varsity Tutors
Varsity Tutors: Hotmath: Algebra Review: Angle Sum Theorem
Find a quick, concise explanation of the Angle Sum Theorem. A step by step explanation of the proof is included to help you understand the theorem.
National Council of Teachers of Mathematics
The Math Forum: Problems Library Geometry Triangles
This site contains a wealth of problems that deal with the basic definitions of medians, altitudes, angle bisectors, and perpendicular bisectors or the defining characteristics of the different types of triangles. There are also...