1) In the book Lemonade For Sale by Stuart J. Murphy, four members of the Elm Street Kids' Club decide to sell lemonade to raise money to fix up their clubhouse, they do it in style. Dressed in special "lemon hats," with Petey the Parrot, the club mascot squawking, "Lemonade for Sale!," business booms at first. Sheri (one of the four members) keeps track on a bar graph, plotting the number of cups sold against the days of the week.

But suddenly sales drop when Jed the Juggler comes to the town and people started to attend his performance rather than buying lemonade from the Elm Street Kids' stand which was located in another place far from the performance. However, Sheri made a suggestion to Jed to juggle right next to their lemonade stand. Next time, when Jed started performing next to the lemonade stand, more people came by and the sales increased more than ever before.   

2) Answer: The book shows in a very simple way the importance of analysis, collecting, organizing, displaying, and interpreting data. It shows how to organize data for a bar graph into different categories. In this story there are two categories; the days of the week (time) and number of cups sold. 

The story also indirectly introduce the idea of x-axis (The days of the week) and y-axis (no. of cups sold), in addition to the concept of function as there is a relation between the set of inputs (the days of week) and a set of permissible outputs (no. of cups sold) with the property that each input is related to exactly one output. 

Moreover, the book demonstrates how people can use graphs to see their business performance (a real life situation) and whether it is growing or declining. The picture below shows how Sheri has plotted the data of their sales in bar graph shape.

After three days of continuous growth; Monday (30), Tuesday (40) and Wednesday (56), the sales shrinks to 24 on Thursday, before it increases again to 90 on Friday (not shown in this picture). The pictures of the book do a good job of showing how graph can be helpful in interpreting the performance of a business visually. 

This literature book also does a very good job in incorporating the economic concepts of producer, consumer, and goods in market.

3) I think literature is a good way to teach students math skills because many of them (as it’s the case for Lemonade For Sale) are applicable in real life experiences, easy to understand and more memorable than equations and formulas. I believe it’s a winning way to make some basic concepts and techniques less intimidating especially for young students.