In this day of modern technology, being able to read Roman numerals isn't all that common. Give your students a leg up on this by teaching them the history of Roman numerals.
Symbols in History
Before teaching your students about the specific history of Roman numerals, discuss the idea of symbolism with them. Talk with students about how symbols evolve from common every day objects and signs. For instance, most of the signs in sign language are derived from common sense, such as the sign for plant which is one hand pushing up through the other as if to display a plant coming from the ground.
Throughout time, written symbols have been developed so that they are easily recognized. For example, stop signs are red because red is the color of blood and has signified a warning throughout time. Even the drawings of early cavemen were based on items easily recognized by that culture. Discuss other symbols that are easily recognized with your students, then move on to the next section on the history of Roman numerals in particular.
Before there were written numbers, people kept count through items. For instance, if a farmer sent 30 sheep out to pasture, he had a stone for every sheep. He did not know the number 30, but he did know to put one stone aside for every sheep. When they returned, he transferred this stones one by one as the sheep came in. If there were stones left over, he did not know a number, he just knew that however many stones he had left was however many sheep did not come home.
Soon, this method of counting evolved into markings, with the most common marking being a slash mark. Romans were very active traders and had many ships. It would have been too difficult for them to keep track of things using only slash marks, so they came up with a system that is presumed to be based on counting on the fingers.
Note that the "I" in Roman numerals is "1" and can be symbolized by a finger. The "V" in Roman numerals represents "5" and is said to be a symbol of the hand outstretched. The "X" in Roman numerals means "10" and is said to be derived from both hands crossing each other.
The most interesting of the Roman numerals comes in the form of larger numbers. There is only speculation to tell us why they are represented as they are. The Roman numeral for 1000 is the letter "M", but is used to be written in what is known as hard or deep parenthesis. It was written as a "C", then and "I" and finally a back wards "C". This cannot be expressed using computer symbols, but it would have looked something like this ( I ). Looking at this one can see how it could be changed to an "M" when written very quickly. Likewise, the "D" that represents 500 was written using the "I" and a back wards "C", so that it would look something like this I ). Again, one can see how that could be turned into a D. The Romans had no concept or symbol for the number zero.
Some of the symbols that were once used in ancient Rome are no longer used today as the use of Roman numerals becomes more and more used for representing years and times in clocks. Some of the older symbols that are not used today are the ones that used a line above any letter to make this letter into a "1000", so that a "V" with a line over the top of it would have meant 5,000.
Talk with your students about the evolution of Roman numerals and why we should learn them today.