Using Spreadsheets to Find Area and Perimeter

The cells of a spreadsheet are a useful way to represent area and perimeter, particularly if you color in blocks of cells. You can link these visual representations to real-world anchors such as walkways, patios, parks, gardens, roller or skate board parks so that students see the connection to their lives.

Building a spreadsheet table to compute area and perimeter also demonstrates the power of spreadsheets to do repetitive computations quickly and to make instant changes when the data changes.

Math Objective

One of the key objectives of these exercises is for students to come up with multiple solutions to the problem. When students work on the spreadsheet files and determine the areas of the different shapes, encourage them to talk about the different ways they solved the problem.

One way to calculate the area of a shape is to break it into smaller rectangles. Another way is to calculate the total area for a rectangle and then subtract the parts that are missing. One other way is to use the SUM command and add up the rows or columns of colored cells. If you use this last method, each cell must have a 1 in it.

Skills/Outcomes
  • Accurately measure and compute perimeter and area.
  • Acquire and use the vocabulary of geometry to describe objects.

Spreadsheet Skills

  • Organize data on a table
  • Write formulas for subtotals and a grand total
  • Use the FILL command

 

What To Do

Materials

Cells Template

graph paper

Files to Use

Download Info/Instructions

area.doc

area.xls

xtraprac.xls

 

Classroom Discussion and Activities

Computer Lab Activities

Added Exercises

 

Classroom Discussion and Activities (Whole Group)

Teacher Note: In the example below, we use a brick walkway for the spreadsheet activity. You may want to discuss the idea of building a walkway with bricks and a wooden border with the students. Make a drawing on the board to aid their understanding. Make up different costs for the materials so that they can use the spreadsheet to calculate the total cost of each type of item as well as the overall cost.

 

 
There are a variety of ways to have students generate plans for the walkway. You could have students "draw, color, and grid" the walkway using graph paper. Use the dimensions of the walkway in the file area.xls.
 
 
You could create costs for bricks, wood for the border, and sand. You will need to provide an estimate for the cost of each of the materials. To extend this problem, you could consider hiring someone to do the work. This would result in a per hour charge in addition to the materials.
 
 
Enter headings and raw data on the template. An example of a cells template with the unit headings is shown below. Through your discussion, you will create the different costs. Students can calculate the total costs using the spreadsheet.

 

Computer Lab Activities (Individual or Paired Work)

Teacher Note: This file contains a graphic representation of the walkway. Students can drag across the different rectangles in the walkway to get the area. The numbers for the area are shown in the upper left corner of the spreadsheet. This portion of the spreadsheet shows the row and column dimensions (e.g., 6R x 3C). Students can use the numbers to multiply the dimensions of the rectangle. This dragging technique can also be used to measure the length of the borders.

Another option is for the students to use the SUM function to calculate the rows or columns of numbers. This is possible because each cell in the walkway and the border has a 1 in it.

 

 

 

Added Exercises

Teacher Note: The following exercises will give students the opportunity to practice finding the area of complex shapes. This will enable you to show students how to derive answers using different solution strategies. Again, students can break the objects into smaller rectangles, calculate the total area and subtract the areas in between, or fill the colored areas with 1's and use the SUM function.