Tessellations Terror!

Yikes!  How can something so simple looking and sounding become so complicated?  I was working with the middle school students on tessellations.  We looked at examples of Escher and they marveled at the drawings. Then it was their turn.  The directions only said to make a cut on one side and the top.  Quickly the students found it didn't work out.  Only with trial and error did they come out with designs that would work even though it took some time.   I guess it was also a lesson in flexibility!