You probably were taught that in grade school, as was I and most certainly your father.  The myth flourished in the 1870's to 1920's period, and for reasons not totally benign. As improbable as it may seem, historians link the spread of the misinformation to an attempt to discredit the ideas of Darwin and promote Creationism (long story.)  The myth has been included in some school textbooks into the current century and most likely to today.

With regard to Columbus, he carried with him on his ship a quadrant and an astrolabe, instruments used to measure degrees of latitude on the globe to aid him in navigation.  For reasons not quite clear, during his first two trans-Atlantic voyages he was unable to correctly use these instruments and at least once he fell back on an alternative method that had been developed by the Greek astronomer Ptolemy (AD 100-170) and which he remembered from his studies.