Provide students with the GeoGebra file Morphing a Rectangle which they can manipulate. Although they can change the location of three of the vertices, the shape always remains a rectangle. This activity can be tackled either individually or collaboratively.
Create a file which illustrates a parallelogram, a square, a kite and a rhombus, all of which retain their quadrilateral type even though three of the vertices can be manipulated. Do not use the polygon tools in GeoGebra.
The Morphing quadrilaterals worksheet is best delivered digitally to your students so that they can activate the hyperlink to the file.