similar parallelograms

Quadrilateral GHJI is a parallelogram. G and H are movable. Drag G and H around, makes some observations, and share what you observed with your group. What changes when you drag the vertices? What stays the same? What aspects of the size and shape of the parallelogram change? Discuss your thoughts with your group. Would you say that every drag of a vertex makes quadrilaterals that are similar? Why or why not? Select the check box to show the diagonal. Drag G and H. Based on what you know about similar triangles, has your argument about similarity been corroborated or debunked?