Parallelogram Properties

Move the vertices around to create different sized parallelograms. Before clicking on each check box, try to make a conjecture about that property. Then click the check box to validate your conjecture.
Complete the Theorems: 1. If a quadrilateral is a parallelogram, then its opposite sides are _____________. 2. If a quadrilateral is a parallelogram, then its opposite angles are ____________. 3. If a quadrilateral is a parallelogram, then its diagonals __________________________________.