CK-12 Foundation
Ck 12: Geometry: Parallelograms Study Guide
This study guide on parallelograms covers types of quadrilaterals, properties of parallelograms and theorems that describe them, how to identify parallelograms, and special types of parallelograms. It is available for download with free...
Illustrative Mathematics
Illustrative Mathematics: G Co Building a Tile Pattern by Reflecting Octagons
This task applies reflections to a regular octagon to construct a pattern of four octagons enclosing a quadrilateral. The focus of the task is on using the properties of reflections to deduce that the quadrilateral is actually a square....