Today I found myself teaching an impromptu lesson on Roman numerals to one of my guided reading groups. It wasn’t a part of my plan at all, but I was happy to quickly change course when a student asked a question about them.
The question itself was fairly simple: she wanted to know what it meant in her book when it said “Chapter VI.” I asked if she knew what Roman numerals were and she said she did not. I asked the rest of the group and they had similar responses. So I quickly turned and pulled out one of my whiteboards and one of my few remaining Expo markers and wrote out the Roman numerals:
I = 1
V = 5
X = 10
L = 50
C = 100
D = 500
M = 1,000
Then we briefly discussed how the numerals are used to express different values. One of the students asked me what they used for zero and I explained that there wasn’t a numeral for zero. They found that very odd but then we continued discussing how to represent various numbers of greater and greater size. I would write some numbers in Arabic numerals and have them convert to the Roman numerals and other times I did the opposite. As they were looking at the numerals, one of them asked what you do when the number is greater than 1,000 and I explained that the convention was to draw a bar over the numerals and that represented “times 1,000.” Then I gave them the big challenge: 2,134,694.
After much discussion, this is what they came up with:
They read it out loud as I checked their work:
“M bar, M bar, C bar, X bar, X bar, X bar, I bar, V bar, D, C, X, C, I, V.”
A student was walking by at that moment and said, “Mr. Valencic, why are chanting a witch spell?!”
We laughed and explained that they were Roman numerals. I think the student thought we were crazy.
What a wonderful way to end a short week before parent-teacher conferences and a day of professional development!
How do you respond to unexpected questions?