What is a parallelogram? Be precise with your definition.
Move points B and D and observe what happens to the parallelogram.
In a quadrilateral, opposite sides are those across from each other, not touching or sharing any vertices. For example, [color=#6aa84f]AB[/color] and [color=#6aa84f]DC[/color] are opposite sides in the parallelogram here.
Is there a relationship between opposite sides of the parallelogram? If so, what is the relationship?
Consecutive sides are those right next to each other (touching) in a polygon. For example, [color=#6aa84f]AB[/color] and [color=#e69138]BC[/color] are consecutive sides in this parallelogram.
Is there a relationship between consecutive sides of the parallelogram? If so what is the relationship?
Now consider the angles in the diagram. Use the checkboxes as needed.
What is the relationship between opposite angles of the parallelogram?
What is the relationship between consecutive angles of the parallelogram?
Now let's add the diagonals to the parallelogram. Diagonals are segments that connect one vertex to another non-consecutive vertex.
Are the diagonals of the parallelogram always congruent? How do you know?
Do the diagonals of the parallelogram always bisect each other? How do you know?
Are the two diagonals always perpendicular? How do you know?
Do the diagonals always bisect the angles at the vertices? How do you know?
What would you say are the most important properties of a parallelogram? Summarize here, and include these properties on your poster.