Leaf Pack Study
Goal for the Lesson
- Students will be able to conduct an experiment using leaf packs.
- access to local stream
- permit to collect macroinvertebrates, if students are 16 or older; available from the DEP
- Leaf Pack from LaMotte Company, or a simple onion sack from the grocery store
- data sheets
- identification cards and sorting charts from the Leaf Pack kit, downloaded from the Internet, or from Golden Guide's Pond Life f rom St. Martin's Press, which is an excellent field guide
- magnifiers and stereo microscopes if possible
- white trays
- petri dishes
- classification keys (class set) (available online at: http://wsrv.clas.virginia.edu/~sos-iwla/Stream-Study/Key/MacroKeyIntro.html or can be ordered through Save Our Streams )
State Standards Addressed: E & E Standards: Watersheds and Wetlands (4.1.7 C & 4.1.10 C)
Teaching Model: Lecture, Cooperative Learning, Sharing
Subjects Covered: biology, environment and ecology, hydrology
Topics: water quality, macroinvertebrates, biotic index
- This lesson should come after students have been introduced to and worked with macroinvertebrates.
- Explain the concept of a leaf pack to students and discuss how they may be used to study a stream community. Involve your students in deciding what will be studied, reminding them that they must have a control leaf pack.
- Divided the class into small groups and have them decide on experimental leaf packs. Some choices of variables may include different types of leaves in the leaf pack or different locations of the leaf pack.
- Have the students develop a hypothesis about what will happen to each leaf pack.
- After students have designed a study and written a hypothesis they should share their ideas with the class and receive constructive feedback. As the teacher you will get a chance to hear all the students ideas and make sure that the experiment is controlled and acceptable. Other students have a chance to hear different ideas and make suggestions about the different experiments.
- Have groups bring in the desired leaves to be tested, each bag will need about 30 grams of leaves.
- Have groups work through the lab activity and prepare the leaf packs.
- Obtain and copy the data sheets from The Leaf Pack Network.
- After each group has prepared their leaf packs schedule time to place them in the chosen stream.
- The leaf packs should be kept in the stream for at least a week, preferably three, then retrieved and brought back to the classroom for the macros to be observed as soon as possible. You will find the most macros in the fall and late spring.
- Retrieve the packs on the day you will be doing the classification activity with your class. If you wait many of the macros will die as the water warms. Most aquatic insects can be refrigerated or kept in coolers with ice overnight. Some invertebrates are very sensitive to changes in temperature.
- The laminated flashcards and the sorting sheets found in the LaMotte Leaf Pack Kit are excellent resources, or use available handouts. Students can classify what they find in the leaves. If your macros are abundant you might also consider preserving some of the larger ones of each type or species for later use and study. Depending on the age and ability of your students, they can simply classify by grouping bugs that are "similar," or try to classify down to genus and species.
- Have students use magnifiers to make careful observations. They should go back and forth between what they are looking at and the handouts, field guide, or cards with the illustrations. Students should record what they are finding and how many of each.
- If available, set up one or more stereo microscopes for the students to look at macros through. These give good detail.
- Students will need to collect and analyze the information that pertains to their study. After they have collected and analyzed the results they will write a conclusion to the study.
- Students may calculate the biotic index of each leaf pack, they may compare the biodiversity of each pack, types of macros found, numbers of macros present, etc. This would have been identified in their experimental set up and hypothesis.
Students will record and organize their results and analyze their results by writing a conclusion based on their findings.
Kristina Rogers, Loyalsock Township High School