MATH CONNECTION!

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Environmental Studies

Estimating Percent Coverage Activity

Description of Activity: This activity and tutorial are designed to develop the skills necessary to study and analyze ecological habitats. Students will learn how to determine the percent covered by objects in a square meter.

Context for Learning:

Explore Question: How do you determine what percent of a square meter and object is covering?

Prediction: I predict that you determine thepercentage of a square meter that an object covers by ………………………………………….

Objectives: As a result of doing the following activities students will know:

How to estimate the percent cover of objects in a square meter.

How to determine the actual percentage of a square meter that an object covers.

Materials/Safety:

                        Journal

                        Activity Sheets

                        4 meter sticks per each group of five.

                        Five different colors, red, green, blue, yellow, and orange, poster board cut to the

following dimensions: (Laminating them after cutting them out will increase their

longivity.)

                                    4 – 40 centimeter squares of each color (16 total)

                                    4 – 30 centimeter squares of each color (16 total)

                                    6 – 20 centimeter squares of each color (24 total)

                                    6 – 10 centimeter squares of each color (24 total)

- 5 centimeter squares of each color (24 total)

                        Note: It might be useful to prepare the students using the percentage tutorial as a homework assignment.

Safety Issues:  There are no safety concerns.

Time: 2 class period assuming class periods of 35-45 minutes each.

Teacher Background:

            When studying habitats it is impractical to even think of being able to locate and count all the different species within that system. Even if there are but a few species within a habitat like a school lawn, counting all thegrass plants would be impossible. To make as accurate of a study as possible,randomly selecting and surveying smaller areas are common practice. Detailedstudying of many of these smaller sampling areas can then produce a veryreasonable “picture “ of the entire habitat. The square meter (quadrat)survey method is commonly used to sample environmental habitats in thismanner.

            To use the square meter sampling technique to survey a habitat requires a bit of training and practice. The first possible. The idea is to have the students learn by discovery. The step-by-step procedure for this activity with examples follows.

Teacher Procedure:

Set up.

Obtain 34-meter sticks and lay out six square meter areas in the location wherethe activity will be performed.

On index cards write the number of each square meter 1 through 6.

Place squares of different sizes and colors into each of the six square meterareas. Squares of similar size but different color are expectable. Try toinclude at least one of each size per square.

Record the actual size of all squares of the same color in each of the square meters for the follow up activity.

Day one.

1. Have the students complete the prediction in their journals.
2. Separate students by counting them off, numbering each student 1 through 6. All the number ones will start at station one the two’s at station two and so on.
3. Distribute copies of the “Estimating Percentages” worksheet. (See below) Tell the classthat their estimating skills are going to be challenged in this activity. They can work as a team to solve the problem of estimating the percentage of area in each big square meter that is covered by the smaller squares of each color.
4. Tell them that they will have towork quickly because they will be limited to 3 to 5 minutes at eachsquare meter. They will NOT be allowed to move or touch anyof the colored squares. They can only look discuss and record. Pointout that if there is more than one small square of any color that theyshould added those together when estimating the percentage that iscovered by that color.
5. Now tell the “one’s” to proceed to square one, “two’s” to square two, etc. At the end of the viewing time they will be given a few seconds to move as a group to the next highest numbered square. When they finish square six they should moveto square number one.
6. Tell them to begin. For the first few rotations give them the full five minutes of time. Circulate among the groups to help them get started and answer any questions. Make sure that they place their estimates for each color in the data section for the square they are currently surveying. (They will notall start at square one.) As they proceed to the later squares thetime can be reduced to a minute or two. You will notice that as a groupthey will quickly develop a system or plan to their task.
7. When all squares have been surveyed have them return to their starting square. Distribute meter sticksand have them measure the actual size of the individual squares(to the nearest centimeter) and then using the second page (See below) of the worksheet and a calculator,calculate the actual percentage that each of the smaller colored squareshas covered in the square meter. Review the instruction on page twoon calculating the percentages
8. Tell the class that the actual percentages for their starting squares will be due at the beginning of class the next day.
9. After each class and before the next class, make sure to randomly distribute the colored squares again. Make sure that you have measured and recorded the actual areaeach color has covered in each square for each class.

Day 2.

Make a transparency of the first page of the activity sheet to display the actual measurements of the colored squares in each of the six squares surveyed theday before.

Begin by asking the team that measured the actual measurements of square one to report the percentage of the square that the colored squares occupied. Then ask each of the other groups to report their measurement. Make sure to correct any measurements in error from your “master” copy.

Next have students complete the “Debriefing “ questions below in their journals. After they have completed the debriefing questions make sure to discusstheir responses.

Debriefing:

How did your group’s estimates compare to the actual measurements of the colored squares in each station?

Did your groups estimating skills get better as you move to later square meters? Why? Or why not?

What plan did your group come up with to determine the estimated percentages?

What was the weakness of your estimating plan? What was the strength of yourplan?

If you were to repeat this activity what would you do differently?

Is their something you could do to the square meters to make the estimatingeasier or more exact?

What practical use is there for estimating percent coverage?

If the colored squares represented a certain plant that was growing in thesquare meters, what would the percentages tell you about the plant?

What is the purpose of calculating the area for the area that was uncovered?

What percent of the square meter did the 10 by 10 centimeter square equal? How many of the 10 by 10 centimeters would it take to make up the entire square meter?

 Look at the grid below. If you were now given a grid like this to do the activity with and you were asked to draw the location of each square how could youmore easily determine the percentage that each covered? What would eachsquare be equal too?

Estimating Percentages

Class conclusion:  Have the students reflect on their estimates, and then have them describe them in their journal as a reflection of howall the areas would fit together and give scientist a way to measure materials and organisms in an ecosystem

Concept Generalization:  After review and discussion, havestudents look at their “Individual Reflection” from earlier and make theirconcept generalization statement. 

Student Generated Question: Direct your students to write questions that they have developed as a result doing this activity.

Next Steps: The next activity deals with another quadrat measurement activity, as well as one that will follow that will measure the number of living organisms.

Assessment Comprehension Questions:

1. What does quadratmeasurement tell you?
2. How might this bea valuable tool to scientists trying to survey very large areas?
3. After completing the activity, do you think that 1-meter square quadrants are an appropriate area to measure?  Why or why not?

Calculating the Actual Percentage Station# _______

• Measure in centimeters, the length and width of each square and record in the tables for each color.
• Multiply the length and width to determine the area of each square. Add the areas together to determine the total area that color covers.
• Determine the total percent coverage of each area by dividing the total area by 100.
• In the last table determine the uncoveredarea by adding the total percentage of each color and subtracting from100 to find out how much was not covered.

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