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An Introduction to Field Data Collection - Part 1
Part 1: Counting the Uncountable

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Author Contact Information

John Nevins
Crandon High School
Crandon, Wisconsin

I can be reached at my school E-mail address: 
 nevinjoh@crandon.k12.wi.us

Overview
This is Part 1 of a series of activities: Acquiring a representative sampling.

The goals of this activity include:

  • A look at the scientific method
  • Student driven experimental design
  • Graphing

    • Grade Level/Discipline
    I use portions of this activity series in my chemistry, physics, biology, and advanced placement biology. Grades 9-12

    National Standards

    Pre-activity set-up
    Have available metric measuring tools and step stools or other ways of reaching the ceiling tiles. Alternatively, use any other surface that has features too numerous to count (e.g., flecks in the carpet or floor; blades of grass. I have also sent students out to find out how many dandelions were on the campus as well as how many pounds of dandelion seed would be produced by these dandelions. I have thought about determining the number of bricks in the school or the weight of the school with this method.)

    Be sure to exercise caution if you use ceiling tiles. We used lab tables as a mode of access to the ceiling. Alternatively, ask the custodians if they have some damaged tiles.

    Materials
    Part 1

  • meter stick or metric tape
  • .1 x .1 m grid cut out

    • Part 2

  • meter sticks or metric tapes 1 per group
  • thermometers 3 per group
  • pin flags or other method of marking out transect lines one set per group
  • graph paper

    • Time Frame
    I have 50 min. classes and the time I use varies with class level and overall objective. Generally the intro takes about one class, the experiment 1 class and the evaluation uses a part of a class.

    Engagement and Exploration (Student Inquiry Activity
    Ask your students how they would find out how many holes are in the acoustic ceiling tiles (or dandelions are in the field). Of course, they could count all of them - but I ask if they REALLY want to spend the time doing that. Brainstorm ideas for the students to collect samples and extrapolate (e.g., sampling a small area and then extrapolating to a larger area or counting along a transect). Let the students try these different suggestions.

    My students do not have an understanding of how a scientist would go about studying a large area. They are concerned about things like global warming or the ozone hole, mainly as a result of news coverage, but they have no idea of how the researchers gather the data and use the data to reach conclusions. As a result, they are not well equipped to judge whether information of the sort used for survey results, population studies and many other forms of data acquired by researchers produces valid information.

    This activity helps to illustrate how scientists collect data from a large area (28,000 sq. km) and use sampling methods to make a judgment of conditions over a wide area while limiting the number of individual field measurements to a practical number. I sometimes like to think of this as counting the uncountable. What is an appropriate method for collecing a sample? How are the data extrapolated? How many samples are needed to be representative?

    This parcticular activity is an outgrowth of one of those “Teachable Moments” that sometimes come along by accident. I was trying to explain the process used by many of their parents when they bid on timber harvesting (we live in the “North Woods” of Wisconsin and quite a few people make a living supplying wood products) and some of my students had their attention else where. I had one of those memories of watching the ceiling and wondering how many holes were in the acoustical tiles. The idea immediately sparked some interest and laughter so I decided to try to find out.

    Explanation (Discussing)
    Ask your students how scientists might collect data on the tundra - for example, the distribution of a plant species or a type of soil. (Alternatively, I discuss how the logging companies figure out how much timber is on a parcel and then I talk about sampling methods. Do the students think that the scientists or the timber company foresters cover the entire area counting each square centimeter - an area that is 100's of kilometers square?) How might the students' ideas for sampling be employed by the scientists to save time and money? How might the satellite images or aerial photos be employed?

    Elaboration (Polar Applications)
    Assign different lines on the floor in the classroom for each group of students to walk along and set a sampling interval for them to use. Each group cut a 10 x 10 cm window in a file folder that would mark out a quadrat to be counted. Each student group moved along their transect stopping at the asigned interval to make a count overhead. (My students were not allowed in this instance to move off of a light fixture or a tile support. I wanted to be able to use the data to figure out the number of lights and support track)

    (An interesting thing happened the first time I tried this one. Our superintendent came through with a board member and several guests on a tour of the department just in time to see my students on stools and lab tables counting the holes in the ceiling. It’s a good thing they are not easily shocked by me. In fact, they acted like nothing unusual was happening in my class.)

    When the students complete their counts along the transect, have them post their results on the board so that all the students can copy the results. Then go through a sample analysis with a part of the data. In that analysis they should calculate the average number of holes in a square meter and multiplied that value by the area of the ceiling.

    (Another bit of information that can be figured out from the data is the number of lights in the room based upon how often the count was zero. When this is done it has poorer results with individual transects than it does with the whole data set from the class. This can help illustrate the degree of accuracy that can be achieved with this method.)

    For example data and calculations see below.(insert table here)

    Exchange (Students Draw Conclusions)

    Evaluation (Assessing Student Performance)
    I require my students to write a lab report that includes the following: Title, Purpose/Hypothesis, materials, procedure, data tables, analysis of data, error analysis, and conclusion.

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