Illustrative Mathematics
Sum of Angles in a Polygon
How can learners use algebra to solve a geometry problem? Help learners create an equation that shows the relationship between the number of sides of a polygon and the sum of the interior angles. Students are asked to divide the...
Mathed Up!
Angles in Polygons
Show your class that finding angle measures is a regular calculation with a resource that provides 12 problems dealing with the measures of angles in regular polygons. Pupils use formulas for the sum of measures of angles in a polygon to...
Mathed Up!
Angles in Triangles and Quadrilaterals
This short video show viewers how to connect the sum of the angles in a triangle to other angle measurements. Pupils determine the missing measures for angles involved with triangles and quadrilaterals. Class members then must explain...
Curated OER
Tile Patterns I: Octagons and Squares
This can be used as a critical thinking exercise in congruence or as a teaching tool when first introducing the concept. Four octagons are arranged in such a way that a square is formed in the middle. With this information, geometry...
Curated OER
A Rectangle in the Coordinate Plane
A quadrilateral is drawn on the coordinate plane, and eighth grade geometers find the length of each side and the diagonals by applying the Pythagorean theorem.
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...