The dots, film or tape you use to keep the ruler from sliding will not prevent a cut from the rotary cutter. You can glue a ruler to the fabric and still get a bad cut. Word of caution: If showing a beginner how to cut either at home, class, quilt shop, or guild, if the beginner was not instructed to use a safety device, not have one for her to use while there, and to use one with no exception to cut with a rotary cutter there could be a lawsuit if the person gets a bad cut.