Thursday, February 01, 2007

Graphing the lemonade stand

From Deb:

Inspired by Raymond's real-life marble business, Madison has been talking a lot about the lemonade stand she will have someday. She'd do it right now, but January in Rochester is not the most auspicious time to have a lemonade stand. She plans to do it at RIT, get sponsored by the math club there, and share half the profits with them. What self-respecting college student, she figures, wouldn't buy a quarter's worth of lemonade from a cute little blonde-haired girl?

Madison talks about the lemonade stand all the time, so I decided to make it our math project for a couple of days. I pretended she already had the stand, and had done it for two weeks. I said that I had given her $10 in quarters to start out, and then gave her the sum total of the cash drawer for each day of the two weeks of the business. From this, she first figured out her sales for each day (subtraction with decimals), then the number of glasses she'd sold each day (division), then the number of glasses she'd sold total (long addition). Then, given that it costed $.05/glass to make the lemonade, the profit (.20 x # glasses sold...and we also did it a different way, with multiplication of fractions: 4/5 of the sales was profit).

And then...she graphed total sales, sales per day, and glasses per day. She loves the graphing. And, I was stunned at this. She graphed sales per day, first, and noticed the zigzags, because some days she had more sales than others. And then, she graphed glasses sold per day, and noticed that the graph was the exact same pattern. Then, she graphed total sales, and at first expected that this graph, too, would be the same pattern. But then it was not. And then, she looked carefully at WHAT it was she was graphing, and explained perfectly why the first two graphs were the same graph, while the total sales couldn't be (specifically, it couldn't go down, she said, it always must go up, unless you spend the money in the middle of the time). Yes!

We're now graphing daily snow levels thanks to the great snow ruler our friends Tom and Susan gave us.

Sorry, Laura, but Madison likes this so much better than Saxon Math.

1 comment:

Anonymous said...

Of course she likes it better that Saxon Math. Raymond would, too. I never claimed that Raymond likes Saxon Math. It's safe to say that he doesn't.


I'm the one who went from Scared of Saxon Math, to Cautiously Optimistic, to Mildly Enthusiastic, and have now decided that I Love it. But it's taken over a year of experience to get there.


Raymond's feelings toward Saxon Math have changed over time, too. He used to Hate it a lot. Now he's mostly able to Tolerate it, and only Hates it on bad days.