Working with Data: Ordering Pizza for a Large Group

There are many occasions for which students and teachers might order pizza. There might be a celebration in class, or a group of students might order pizza for a social event. Students and teachers need to determine a fair method of sharing the cost of the pizzas that are ordered. This lesson takes advantage of many spreadsheet commands and formatting options (e.g., whole numbers, currency). More importantly, it allows students to evaluate data using a variety of operations (e.g., multiplication and division). Students will need to think about how to set up the problem and how to change data. For example, what if each student wants to order 4 slices of pizza instead of 3? Perhaps the most important part of the lesson is when students compute that they will need 3.25 pizzas. How many should they order-3 or 4?

Classroom Discussion and Activities

Computer Lab

Classroom Discussion and Activities (Whole Group)

1. Introduce students to the problem of ordering pizzas for a class or large group of people. Who will pay? How much will each person pay? What would be fair? Should you include tip and tax? Ask individual students or teams of students to come up with solutions. There is a worksheet (pizzawst.doc) included in this document that can be used individually or by teams.
2. Develop a spreadsheet table using at least two different class sizes. For example, develop a spreadsheet for a class of 28 students and one for a class of 34 students. This will help students see how the spreadsheet is a convenient tool for changing basic quantities.
3. Build a spreadsheet in class using the overhead projector while the students build the spreadsheet on grid paper (see gridport.doc for sample paper spreadsheets). Look at pizza.xls to see a model of a finished spreadsheet.
4. Decide on basic information about one pizza, such as cost, amount of pizza to be ordered, etc., that will go into the row that contains the labels. We call this row the "header." Header information can be changed for different companies or sizes of pizzas. 
5. Decide on what data or labels to put into the columns. This means you must decide about text, numbers, and formulas. Thinking about all of this before you go into the lab-and having students use paper and pencil to plan the spreadsheet-saves time in the lab and gets them to organize their thinking. This will promote problem solving rather than just "punching in" numbers and data. You can collect gridport.doc worksheets from students as daily work. 
6. Work out the formulas with the students. Have them write the formula on their paper and pencil worksheets in an appropriate cell. Be sure that the formulas start with an equal sign. A formula would look like this: = B9/C9. This practice will help the students see the logic of formulas in spreadsheets. It is also an opportunity to talk through what the operations are and why you are doing them (e.g., "Why are we dividing here?").

Before you go to the lab, you may want to talk about cell formatting issues. You will probably want to use the currency format for some columns. You'll want to make sure that the other cells are also formatted to show decimals to the 100ths place. Discuss how many place values are needed and how to format for the desired place value. Students can make notes on their planning sheets about format to use for various cells.

Computer Lab Activities

• Complete spreadsheet

• You may want to use a template that you have prepared or have students use their own that they have prepared in class. Enter the numbers, text, and formulas from the sheet. Make sure that they double check their work. This activity will enable students to see if their answers make sense. 

• Discuss the spreadsheet. Here are some sample questions.

 

"No matter how many additional people you feed, the price per person always remains the same. Why?"

 

"How should you handle ordering pizzas when the chart says to order a fractional part?"

• Copy spreadsheet to another sheet within the same workbook or file. 

• Here are some sample activities that will enable students to make changes in the spreadsheet and ask "what if" questions:

 

Change the format of the Pizzas Needed column so it rounds the pizzas to the nearest whole number. If you did this in a real situation, would you be ordering enough pizzas?

 

You need to feed hungry students. They want four slices of pizza each. How many people will one pizza feed? What else would you need to change?

 

• Ask the students to suggest other changes. They can keep copying the charts and making changes to the newest copy.