Lets try an activity using translation vectors to form a tessellation.
Use the following parallelogram and the Geometer’s Sketchpad to work through the activity. If you don’t have the Geometer’s Sketchpad use the third link to try a tessellation activity on  Microsoft Paint
Sample Parallelogram
Sketchpad Activity
http://mathforum.org/sum95/suzanne/tess.gsp.tutorial.html
Use the window bars at the bottom of the screen to switch back and forth between the instructions and Geometer’s Sketchpad.
http://www.wsd1.org/bitsbytes/9798/bboct97/default.htm#STORY4