# Peyton Manning Offers Students a Lesson in Math and Finances

Thursday marks the return of professional American football, that sweet, glorious sport that steps in every autumn to finally save us from baseball.

Football's supreme popularity has led to a number of activities trying to capitalize on the fun, but here's a new one from ESPN: A stock market game.

Instead of investing in companies, students buy stock in quarterbacks, and the performance of that quarterback over the season determines the payoff. The game uses a quarterback's passer rating (also known as a quarterback rating), which is based on a player's passing attempts, completions, yards, interceptions, and touchdowns. ESPN's Scott Van Pelt and Ryen Russillo have a breakdown already available. The gist is that students get \$1,000 to invest in quarterbacks from multiple tiers.

Here's where it gets a little wonky. The stock game uses the following formula:

where QBR is the passer rating, W-L is the win-loss differential, and p is stock price. (I call it the Peyt-thagorean Theorem.*)

An important note here: ESPN's QBR system is different from the official NFL system; the sports media company says that the NFL's system doesn't capture every aspect of what makes a quarterback good, so they've adjusted passer ratings to a modified scale. Critics of ESPN's system say that it unfairly elevates bad quarterbacks who just had a lucky situation.

The point of this is just to say that, should you end up using this stock market game, make sure you're staying statistically consistent.

Example: Under ESPN's system, Peyton Manning has a QBR of 82.9 (from the 2013 regular season). 82.9 divided by 10 is 8.29. His 2013 regular season record was 13-3, which means he won 10 games more than he lost. Therefore: 8.29+(10/4)=\$10.79 per share.

Under the official NFL system, Manning would have a passer rating of 115.1, which ultimately boils down to \$14.01 per share.

(In theory, it might make more sense to start the stock game after Week 1, because the formula relies heavily on win-loss ratio.)

At the end of the season, students sell off all their stock and see who did best; they can watch as New York Giants quarterback Eli Manning gets his 157th interception of the season and his stock plummets.

The game relies on students being able to understand how new NFL players or coaches can change a quarterback's performance. For instance, Tom Brady, of the New England Patriots, had a pretty bad 2013 season (NFL passer rating: 87.3), but in the off-season, his team developed its offense and traded for some star defensive players, which means the Patriots will likely improve this year.**

If you'd rather focus more on straight math than financial literacy, then maybe have your class try fantasy football instead, which also relies on an understanding of statistics and arithmetic. Bryan Toporek, over at Schooled in Sports, has a great breakdown of what that entails.

Alternatively, you can also use the NFL teach your students about sports safety, pay discrimination, and healthy relationships.

Let's go team!

*Patent pending

**... I write with a certain hopefulness.

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