What might first seem like a mistake can lead to much more interesting thinking.
I began class asking this question. While it’s not a very good one, it’s a hell of a lot better than most questions that get asked in a math class. After my students got past the fact that 7+7 does not equal 2, here’s what they came up with.
What if “+” doesn’t mean what we know it to mean? Perhaps it means we are to COMBINE the sevens to make a two. If we rotate one seven 180 degrees, and then overlap their stems, that would produce a two.
Alternatively, one might think that each 7 is its own “idea” or “entity”. One idea plus another idea is 2 ideas.
Or maybe those sevens aren’t really sevens, but just badly drawn ones?
Then again, if it’s 7:00 and 7 hours pass... well, then it’s 2:00, isn’t it?
One of my students suggested that 7+7 is two sevens, so perhaps the equation shows how many of each number there are. So, for instance, 7+7+7 would equal 3.
Or better yet, let’s play with units. 7 days plus 7 days equals 2 weeks.
