Think of the word convert as meaning change, whether it is a person who adopts a new belief, or a changing action, such as when you convert dollars into euros. Many times we can catch a word's meaning by looking at its origins. In this case, the Latin con means around, while vertere means turn..
Maple sap runs best when it freezes at night (e.g. in the high 20-degrees Farenheit range) and then warms up above freezing the next day (in the range of 40-degrees Farenheit and hotter). If it stays warm at night and warm during the day or if it freezes at night but barely goes above freezing the next day, sap does not flow as well or hardly at all.
A sugar maple that is 10 to 12 inches in diameter at chest height will be about 40 years old and gets one tap. Some large maple trees in Vermont sugarwoods are over 200 years old! Vermont sugarmakers tap conservatively, so a tree yielding sap is like a person donating blood.