Let's do the math: there are 10, count 'em, 10 different investigations here, all wrapped up in one neat package. They are themed around the applications of percents. Each one highlights a different feature of percents that your students should know about in order to be good consumers and astute citizens of this democracy.
Here is what you'll get:
• It's a Deal: Many stores offer "buy one, get the second half off." This activity looks at what the percentage off in each case, and asks students to compare which is the best deal.
• How Do You Tax and Tip: When you eat in a restaurant, did you notice that your bill now has "suggested tips" on them? Well, some restaurants have found a nefarious way to make you pay more tip than you should.
• Deal or No Deal? Should you take cash off or percent off? In this scenario, you be the judge when one is better than the other, or they're the same.
• Automatic Money: ATM machines charge you a fee every time you take out money, and their fees vary according to location What percent of your money goes to the machine when you use an ATM?
• Political Percents; A politician promises to cut income taxes by 30%; do the math and see why his promise is impossible.
• Want a Raise? Your boss offers you two options for a raise: 2% a year, each year for 5 years, or just one single 8% raise. You'd be surprised which one is better....
• How Much Does Your Money Cost? Those gift cards from Visa are very popular. That is, until you factor in the "price" for those little pieces of plastic.
• Money at a Discount: Got a gift card to Applebees for your birthday, but hate their food? There is a website where you can sell your card, but you won't get 100%. Use percents to figure out how much you'll get for this "gift."
• What Goes Down? Do you know that if you purchase a stock and the price goes down 10% in value, you won't "break even" if it goes up 10%? Do you also know that it is better for your stock to go up 5% two days in a row than 10% in one day? Find out why!
• What's in Your iPhone? iPhones sell for $650, but they don't cost nearly that much to make. This activity looks at the various components used to make an iPhone, including labor, and asks students to figure out what percent of the manufacturing cost it is. The students then figure out what percent of the actual sales price it is. Is Apple doing well with the iPhone? You wouldn't believe how well is "well."
These are individual activities that can be given to your class and discussed in a single class period. They include writing prompts to analyze what happened, and, of course, there's even an answer key. You can use these as emergency lesson plans for a substitute, set them up in a "challenge file," or turn them into task cards. Your kids will LOVE percents after doing these investigations (and they might be smarter about their own finances....)
If you like this, check out this: The Mathematics of Economic Justice: Wealth Distribution in U.S.