How to cut large squares

OK have had a few friends ask me how to cut large squares if you don't have a massive square ruler. Now this method is not the best if you need absolute accuracy.... but when in patchwork have we needed absolute accuracy :)

This is actually the second cut but I can't find a photo of the first cut.  As the principle is the same you can follow from this. Place your ruler onto your fabric near the edge, lining up the edge of the ruler with one of the line markings on the mat. Hold the ruler down firmly and while pressing down cut away from yourself.  For a more accurate cut, and to lessen the chance of the ruler slipping,move your hand along the ruler when making long cuts.  Only cut 6-8 inches before moving your hand along the ruler.

If you have a large enough mat, for the fabric to lie completely on it, then turn the mat so that the cut edge now lies along the side closest to your body.  If your mat is smaller, then simply turn the fabric lining up the cut edge with one of the marked lines on the mat. Line up the cut edge of the fabric with one of the lines on your ruler.  Slide the ruler so that the edge is near the edge of the fabric and lies along one of the marked lines on your mat.  Taking care cut away the excess fabric. Rotate the fabric and mat again. and repeat the above steps.