Explain what spreadsheets are and how they work, including the following features:

• A spreadsheet is a computer program that lets one organize information in a grid of rectangles, called cells, and do calculations. There are many different spreadsheet programs, but they all work in basically the same way. The rows are labeled with numbers and the columns are labeled with letters.
• Display this image of a sample spreadsheet.
   

  

  A 4 coulumn spreadsheet with 3 rows of data. The heading for Column A is "Ingredient." The heading for column B is "Weight, in pounds." The heading for Coulm C is "Unit cost, per pound." The heading for Column D is Cost, in dollars." The data for the spreadsheet are as follows: Row 2: Cheese; 3 point 6 pounds, 4 point 5 zero dollars, 16 point 2 zero dollars. Row 3: Raisins; 1 point 6 pounds, 2 point 5 zero dollars, 4 point zero zero dollars. Row 4: Peanuts; 2 pounds, 3 point zero zero dollars, 6 point zero zero dollars.

  Ask the students, “What information is in cell B3? What does this piece of information mean in terms of the situation?” (1.6; how many pounds of raisins there are).
• It is helpful to put headings in the first row that describe what information goes in each column (and headings in the first column to describe each row). It is also helpful to organize the information in the spreadsheet to be read from left to right and from top to bottom.
• If a formula is typed correctly into any cell of a spreadsheet, the program will calculate and display the value of the expression. Formulas must start with an equal sign. If the answer is not a whole number, the spreadsheet will display the value as a decimal. It is possible to program each cell to round decimal values.

Note that spreadsheets on tablets are a bit different.

• The “enter” key on the keyboard is usually at the lower right, marked with a right-angle arrow pointing down and left.
• The Numbers spreadsheet involves less typing. Instead of typing “=” and a formula, tap the “=” button; tap a cell whose address is wanted in the formula; type numbers and operations. If there are typed headings, the words will appear in the formula, such as “Amount (lb) Cheese.”

A spreadsheet and a calculator on a tablet are indicated. At the top of screen, is a sample 4-column spreadsheet with column A titled, “Ingredient,” column B titled “Amount in pounds,” column C titled “Unit cost in dollars per pound,” and column D titled “Cost.” Row 2: Cheese, Amount in pounds, 2; Unit cost in dollars per pound, 4 point 5 0 dollars; and Cost, blank. Under the cost column, the formula for each cell shows “equals, Amount, in pounds, of cheese” times “unit cost, in dollars per pound, of cheese.” At the bottom of the screen, on the left are the following buttons : open parenthesis, closed parenthesis, comma, percent, multiplication, addition, to the power of, division, subtraction, ampersand, less than and equal to, and not equal to. In the center is a calculator with a number pad and to the left are the following buttons: functions, a b c, calendar, true/false, delete, right, and enter.

Provide access to spreadsheets. Give students quiet work time followed by whole-class discussion.

Use Collect and Display to create a shared reference that captures students’ developing mathematical language. Collect the language students use to discuss spreadsheets. Display words and phrases such as “cell,” “box,” “formula,” “number,” “row,” and “column.”