It was thinking this morning, as I sat with my young son, how remarkable it is that we measure distance with units called 'minutes' and 'seconds'. We were playing with the book 'Tick Tock Sharks' which uses a shark themed poem to teach time telling with a representation of a clock in the middle of the book. A dial using two concentric rings moves the hour and minute hands, and an associated digital dial providing the numeric time, i.e. 05:00 and so on. The units "minutes and seconds" are used not only to measure the span of time it takes a clock hand to rotate around a clock face, but to indicate the divisions between the lines of latitude and longitude that navigators use to indicate locations on the surface of the earth.