Facts that turn the "6-7" meme into a teachable moment
You have probably heard kids say "6-7", all while alternately raising the palm of one hand and dropping the other. Last year, I was the pastoral teacher for a Grade 8 class that met in room 67. Can you imagine how many times I heard it?!
I don't know interesting facts about "6-7", but the number 67 itself is fantastic. It is a prime number that can be expressed as the sum of 5 consecutive prime numbers!
67 = 7 + 11 + 13 + 17 + 19
Those five primes, taken in pairs, have interesting relationships too:
- (11, 13) and (17, 19) are each a pair of twin primes: Prime numbers that have a difference of 2.
- (7, 11) and (13, 17) are two pairs of cousin primes: Prime numbers with a difference of 4.
- Do you know what the pairs (7, 13), (11, 17) and (13, 19) are called? I have learnt to get the students to look the answer up. In the past, I would tell them and they would look at me as if to say, "You're pulling my leg, aren't you?"
While there are other such "fantastic" primes, we're trying to impress kids who come to us with their "6-7" meme, so let's put the others to one side today.
If you're interested in a couple of angles to show the relevance of primes to your students, take a look at this article.