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.
The Rule of 86. How many gallons of sap does it take to make one gallon of maple syrup? Using the Rule of 86, you can figure that the number of gallons of sap you need to produce one gallon of syrup is equal to 86 gallons divided by the percent of sugar in the sap. So if you start with sap that is 2% sugar, you would need to evaporate 43 gallons of water (86 gallons / 2% = 43 gallons) to make one gallon of syrup.