NOVA Online | The Wilds of Madagascar | Transect Investigation

Transect Investigation

Lesson Objectives

By the end of this activity, students will be able to:

subdivide an area into transects and perform a scientific study.
use a magnetic compass to determine the N/S and E/W directions in the transect.
grid the transect and transcribe the biotic and abiotic information accurately on paper.
create their own map scale.
combine class transect data and make some general conclusions about the area.
predict how a drought and flood rains might affect the area.

Related National Standards

National Science Education Standards (National Research Council)
Grades 5-8
Science Standard A: Science as Inquiry

Identify questions that can be answered through scientific investigations.
Design and conduct a scientific study.
Use appropriate tools and techniques to gather, analyze, and interpret data.
Develop descriptions, explanations, predictions, and models using evidence.
Think critically and logically to make the relationships between evidence and explanations.
Recognize and analyze alternative explanations and predictions.

Grades 9-12
Science Standard A: Science as Inquiry

Identify questions and concepts that guide scientific investigations.
Design and conduct scientific investigations.
Use technology and mathematics to improve investigations and communications.
Formulate and revise scientific explanations and models using logic and evidence.
Recognize and analyze alternative explanations and models.
Communicate and defend a scientific argument.

Materials needed for each group

outside area such as a park, meadow, or forest
string
wooden pegs
meter stick
paper
red, green, and blue colored pencils
compass
copy of Transect Study activity sheet
poster board

Estimated Time to Complete Lesson

It will take one classroom period to take the students outside to gather their data. A second period will be necessary to combine all the students' data into one report of the area.

Teaching Strategy

Background Information
One method scientists use to study an environment more closely is to divide the area into smaller plots called transects. A scientist can record the location and number of different animal and plant species that occur in the transect. Abiotic (nonliving) factors can also be recorded depending on the level of detail required by the study. If the area is rather homogeneous (the same throughout) fewer transects need to be analyzed in order to draw some general conclusions about the area. The more varied the area the more transects need to be analyzed in order to make accurate general conclusions.

For some species such as certain weeds (like dandelions) it may not be realistic to count the number of individual weeds in the entire transect since their number is so large. In such cases a tiny area of the transect can be selected where the weed is counted and then by the use of multiplication the scientist can calculate the estimated number of weeds that occur in the transect (since the weed growth pattern is not identical throughout the area).

Procedure

Organize students into groups and provide them with a copy of the Transect Study activity sheet.
Assign each group a transect (an area of five feet by five feet) to study. Have students stake out their area using the wooden pegs and rope. Identify each transect by number.
Using the compass have students determine their N/S, E/W orientation and record this information on their activity sheet.
Have students `grid' their transect by using the pegs and string. For example, they may put a string across the transect every foot both in the north/south direction and in the east/west direction. In this way they can more accurately locate the geographical features on their transect as they record them on their activity sheet.
Students should pick out and record the most distinguishing features first. They should record what they see (naming the species if possible) and the amount of what they see.
Students should use the colored pencils to indicate grass (green), water (blue), and soil (brown).
Have students note any effects on their transect due to human activity.
Return to the classroom and combine all the transects together on a poster board, synthesizing the information into one document describing the area of study.
Have students comment on the following:
- What generalizations can they make about the area?
- When all the transects were combined, was the area the same throughout or different and why?
- Did they see any effects of human intervention on their transect? Was it harmful or beneficial?
- How does the area get water? How would the area withstand a drought? Flood rains?
- Is the area in danger of dying out? If so, what is the threat and how soon? Is there anything that can be done to prevent death to the area?

Helpful Web Sites

The Virtual Library of Ecology and Biodiversity
http://conbio.rice.edu/vl/

Specializes in reviewing Internet information sources pertaining to ecology and biodiversity based on their educational value.

Plant Taxonomy—Ecology Net Links
http://ecology.about.com/education/ecology/msub60.htm

Provides several links, including one to the USDA Plant List, to help identify plants.

Assessment Recommendations

Students may be assessed through:

their participation in the outside portion of the activity.
the accuracy and level of detail they provide on their transect study.
the accuracy of the map scale they devised.
the generalizations they make about the entire area once class data is combined.
the quality of their predictions as to how drought and flood rains might affect the area.

Extensions/Adaptations

Research and write a report on some of the species they found. Let students choose which of the plants and animals they found to research. Have them look for such information as the animals' natural distribution, life cycle, and predator-prey relationships in the food chain.
Design a bulletin board that displays the transect study. Make sure to include some of the information that the students found in their research (from Procedure Step #1 above).
Return to students' transect every two months. This way, students can see how the population changes depending upon certain variables, like time of day, temperature, or season. Students who keep a log of the changes can return to their data and look for patterns and make predictions about what they might see at the same spot in the future.

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