standard_description: Understand that attributes belonging to a category of two-dimensional figures also belong to all subcategories of that category. For example, all rectangles have four right angles and squares are rectangles, so all squares have four right angles.
problem_activity: Task
Suppose $\overline{AB}$ is a line segment and $D$ is a point not on $\overline {AB}$ as pictured below:
[IMG]
Let $C$ be the point so that $|CD| = |AB|$, $\overleftrightarrow{CD}$ is parallel to $\overleftrightarrow{AB}$, and $ABCD$ is a quadrilateral.
Draw a picture of this situation and
show that $ABCD$ is a parallelogram.


aligns: no