Math = Love: Relations, Functions, and Dating Advice

## Tuesday, September 24, 2013

### Relations, Functions, and Dating Advice

I guess I shouldn't be surprised when my students give me dating advice.  After all, I gave them some dating advice a few weeks ago, and they must be just returning the favor.  If you want to know what your students really think of you, let them write you an online dating profile.  But, more on that scenario and how it came to be at the end of this post.

After spending several days on relations and functions in Algebra 2, I put up this slide.  Mathematical Dating Advice.  Yes, the room will grow quiet.  Conversations will cease, and all eyes will be on you.  You will be shocked at the rapt attention that your students are capable of paying you.

When you are dating, you want to be in a functional relationship.  Let the x-coordinate of the ordered pair be any person.  In this case, the x-coordinate is Bob.  Let the y-coordinate of the ordered pair be the x-coordinate's significant other.  As you can see, Bob is dating both Jill and Sue.  Therefore, this is not a functional relationship.  And, unless you want to get your heart shattered in a million pieces, you need to get out of this relationship as fast as possible.

After this short conversation, I think I saw some light-bulbs come on.  There was laughter, and I heard several girls discussing how they were going to ask the next guy they were interested in if he was a function or non-function.  They decided this was problematic, though, because he wouldn't know what they were talking about if he hadn't taken Algebra 2.

As students were working on their function/not a function card sort, one group of students called me over for what I thought was help.  Actually, they had been discussing my advice, and they had decided that one of the girls was currently talking to a guy who was definitely not a function.  So, could I please tell their friend that she should stop talking to this guy?

Fast-forward to about 2.5 weeks ago, my Algebra 2 students are now working on distance vs. time graphs.  We're doing graphing stories.  We're writing stories to match graphs.  And, this is leading to a lot of off-topic conversations.  It's a Friday, and the class consensus is that we would all rather be at the beach than analyzing graphs of walks at the beach.

And somehow, one comment leads to another, and my class is soon discussing how I should describe myself if/when I try online dating.  This is what they come up with:  "I like taking long walks along the beach and graphing them.  I love reciting the quadratic formula.  And, I enjoy reading math books by a roaring fire."

I guess I should be thankful that they are concerned about my relationship status.  But, I don't think I will be taking their advice any time soon...

1. Thanks! My students loved it, too!

1. Did you talk about a situation like (Bob, Jill) (Jeff, Jill)? Just wondering if that came up in conversation.

1. I let the kids bring this up, and then we discussed whether it met the requirements of a function.

2. Brynn, that was my first thought! I generally use a "soda machine" approach when exploring functions. Press the cola button, out comes a can of cola ---> Function. Press the root beer button, and sometimes a cola comes out while other times a root beer comes out ---> Not a function. Having two buttons for a cola is okay, as long as, when you press either one, you get a can of cola. Love the dating analogy, but Bob, Jeff and Jill may confuse things a bit.

1. Oooh! I like the soda machine analogy. I've never heard it explained exactly that way before!

3. If you always put your ordered pair in (boy,girl) form, then you could say that it's OK for a girl to date two boys, but a boy can only date one girl.

4. I loved the post. I've never thought about connecting relationships with relationships. It is too bad that the lesson on functions did not line up with one of those romantic holidays in late October or the middle of February. I noticed GGGardener’s comment about the social norms of being expressed in the in the analogy and the possibility of a girl being dated by two guys. I guess it does bring up the option later on when you talk about invertible functions.

An article you might enjoy reading is by Manil Suri and showed up in “The New York Times”.
http://www.nytimes.com/2013/09/16/opinion/how-to-fall-in-love-with-math.html?_r=0
The editorial is called "How to Fall in Love With Math."

1. Enjoyed the article you linked to. Thanks for sharing!

5. I do that with my kids but I have the girls as the X and Boys as the Y, since Chromosome wise girls are XX and boys are XY. They seem to get it. I get answer all the time that the X cheated and they are not suppose too, or the guys can cheat. I don't let them answer that way on a test or quiz , I tell them I want the definition but it help them understand it better because it relates to them.

6. My Algebra 1 kids had a lot of fun with this idea. They now refer to the "dating rule" when discussing functions and relations.