Part 2: Count Me In
Before we can build a runway, airport or test any new aerospace equipment, it is wise to
conduct an environmental impact study. The study will help us determine whether our
activity in the area we’ve chosen will affect any of the many environmental factors that
are present. In some instances, we need to attempt to determine our impact on a
certain type of plant or animal life. Researchers calculate the size of an animal
population in the wild by capturing some specimens and marking them. The marked
specimens are released and the researchers wait for an appropriate interval to let the
population move and get back to normal. More captures are made and this time, some
of the specimens captured will be some of the specimens previously tagged and
released. Others will be specimens that have not been captured and tagged before this
time. By counting the tagged and untagged animals after each trial, the researchers use
ratios to attempt to calculate the size of the actual specimen population.
This sortie requires you to conduct an experiment to attempt to determine the size of
the population of a local type of tree lizard. The local area in question will be used to
test new aerospace systems. You and your teammate will model the method used by
researchers in the field. You will start with a population of tree lizards selected by your
sortie facilitator but unknown to you. By conducting a number of “capturing” trials,
sample tree lizard specimens will be counted and tagged. After tagging (with a rubber
band) and recording the starting number of specimens tagged, the specimens will be
released back into their “habitat”. After the first trial, a record will be kept of the number
of tree lizards captured that were tagged and the number that were untagged. These
specimens will all be released back into the habitat.
After the trials are completed, your team will analyze the numbers of tree lizards
captured in all the trials, compare the numbers of lizards that were tagged and the
numbers of lizards that were untagged and will attempt to determine the size of the
population in a specific area. Your team’s estimated population size will be compared to
the actual population number. This sortie will help you learn how to collect, record,
organize, and interpret data collected during an experiment.
Location Coordinates: (
,
)
A. Pre-Sortie Instructions
1. The sortie facilitator will set up eight research stations. Each research station will
require an event timer to help students keep track of time elapsed and time remaining.
The rubber bands will be used to “tag” each specimen before it is returned to the
habitat.
2. The sortie facilitator will determine the number of specimens to place in each habitat.
3. The sortie facilitator will divide you into teams of two.
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February 2009 / 0612
3. Your team will be assigned a sortie station.
Station 1
Station 2
Station 3
Station 4
Station 5
Station 6
Station 7
Station 8
4. You will need a data collection sheet for each team member.
5. You will be assigned roles as researcher and data collector. You will alternate roles
for each trial.
6. Make certain your event timer is reset to zeros.
7. The sortie facilitator will assign you a predetermined number of trials to complete.
8. You should have a”habitat” with lizard specimens and rubber bands to tag them.
9. Once you are ready ask the sortie facilitator for permission to begin.
B. Task
1. Once given permission to begin, the researcher will take 20 specimens from their
habitat and tag them. All captured specimens will be tagged before they are returned to
their habitat.
2. For the first trial, the researcher will take out 20 specimens. The specimens will be
examined. The data collector will record the number of specimens that are “tagged”
and those untagged.” The untagged specimens will be tagged and all specimens will
be returned to their habitat.
3. Twenty specimens will be captured form the habitat for each trial. The data collector
will record the number of specimens tagged and untagged on the SLOF. Once the data
is recorded, all specimens will be tagged and returned to their habitat. This procedure
will be repeated for as many trials as directed by the sortie facilitator.
4. The data collector will record the data in the SLOF for each trial. After the
researcher completes his / her trial, roles will be exchanged so each team member
ends up assuming each of the roles for several trials. Students will continue to alternate
turns as researcher and data collector until they collect the data required by the
SLOF.
Students will use the appropriate section of the SLOF to record their collected data.
5. Remember to keep track of the elapsed time and time remaining.
6. Confirm you have data recorded for each trial.
7. Ask the sortie facilitator if there are any additional instructions.
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February 2009 / 0612
8. Complete your population calculations and estimates.
9. If there are no further instructions, turn in your data collection sheets to the sortie
facilitator.
.
Post Activity
1. The sortie facilitator will direct you to “untag” all the specimens you tagged during
their research. Return all now “untagged” specimens to the habitat.
2. Reset the event timers.
3. Collect your personal items and prepare to move to your next sortie.
Property of Engineers For America STEM Initiative and not to be copied in part or whole without permission.
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February 2009 / 0612