Overview & Lesson Sequence

Focus on Standards & Assessment

Materials Needed, Preparation & Planning, Management Strategies

Background Info

Intro Activity
Why Study Predator - Prey interactions?

Activity 1
Observation of a predator-prey interaction

Activity 2
What makes a predator successful?

Research Project
Designing a predator - prey experiment

Optional Activity
Biological Control vs. Pesticides

Case Study
Rabbits in Australia

References

Glossary

Suppliers

Resource Sheets

Enforcers Home

CISEO Home

Research Project : Design a Predator-Prey experiment

For this project, students will use some of the laboratory techniques and information from Activity 1 and 2 to design their own experiment. Students will be engaged in inquiry as they collect, organize and analyze data in order to answer their own questions.

Depending on the question they are asking and the research design, the projects can take approximately five days with students spending the entire class period observing and recording data, or one to two weeks taking approximately 15 minutes of class time per day.  Students will be making initial observations, formulating a research question and hypothesis, and gathering data to answer their own question.

When everyone is finished or at the end of an assigned period of time, students will present their data to the class. You may want to have a poster session instead of individual presentations. In either case, students should present the experimental design, the data, and conclusions based on the evidence.

Note
Because students may be working at different rates and taking differing amounts of time for doing their projects, you may want to have other individual activities planned such as searching for information on the Internet and/or other ecology assignments. You may want some of the students to start setting up the control-treatment study (Activity 3).

Class time required
Approximately 5 full class periods or 2 weeks of 15 minutes per day

Materials needed
Per group:

• 3 or more Petri Dish Habitats (see Petri Dish Habitat instructions)
• at least one aphid infested host plant
• 1 water soluble marker
• 1 grease pencil
• clear cellophane tape
• clock with second hand or stop watch
• ladybird beetle adults and larvae
• lacewing larva
• praying mantids (optional)
• big-eyed bugs (optional)
• soft forceps, small paint brush, or eyelash brushes (see Eyelash Brush instructions)
• dissecting microscope or other strong magnifier
• Predation Inquiry Lab sheets

Preparation
Refer to the "preparation and planning" section at the beginning of this lesson for instructions on how to grow pea plants and infest them with aphids.

Prior to this activity, choose, order and/or rear at least three different species of predator to be used in the experiment (green lacewing larvae, adult lady bird beetles, lady bird beetle larvae, praying mantids, big eyed bugs). Some predators, such as lacewings, can be ordered a few days to a week before the experiments.  Others, such as praying mantids, must be reared from egg cases which can take several weeks to hatch.  Refer to the rearing sheets for each of the predators for more information.  You may also want to check with the various suppliers in advance to determine availability.  Plan on ordering or collecting at least five of each species of predator for each student group.

Procedure
Tell students they will be designing their own experiment. If they have previously conducted experiments to answer their own questions, they may not need the Predation Lab sheet.  Begin by addressing the students with the following questions: Given your observations of the different predators and knowing what makes a predator successful, what are some questions you might ask? (Do plants with predators on them grow better? Which insect is the best predator? Do predators compete and if so, in what ways?)

Since the materials presented for this project focus on quantifying predation success among species, you may want to highlight the student responses that lead in this direction. Help students focus on researchable questions (i.e. questions with quantifiable answers and questions that can be answered in a relatively short period of time.)

Distribute the Predation Inquiry Lab sheet  and, as a class, review the questions under "Investigation Design". Define terms and clarify meanings as needed, then have teams complete their  experimental designs.  After reviewing and comparing investigation plans, schedule and announce specific days on which predators and/or prey, and fresh plants will be available. This will allow each team to finalize an investigation timeline.  Once the investigation designs have been checked, modified and approved, teams may begin assembling materials and apparatus and conduct their investigations.

Presentations
Students can prepare a poster session displaying their data (as they might for a Science Fair) or make group presentations to the class. Each poster or presentation should include the group’s question/hypothesis, materials, data collection methods, data displayed in a chart, table or graphs, and a conclusion.

Using a chalkboard, whiteboard, or overhead projector, outline the investigation results of the entire class.  Highlight the more extreme experimental results (outliers) and those that were inconclusive. Note difficulties encountered and successful strategies. Ask comparative "why" questions such as: Why did the Group 3 lacewing larvae eat more than the Group 1 lacewing larvae?  Ask the class to give an oral summary of the overall results of the investigation while relating findings back to the big conceptual ideas of the lesson.

Assessment
As students design and carry out their research projects, use the Observation Check sheet to record students' attainment of the learning objectives listed at the beginning of the lesson.  Review students' journal entries and/or charts to determine what levels of conceptual understanding they are developing.  Students should be able to come up with a researchable question and design a simple experiment to try to answer that question.  Use a presentation rubric to assess evidence used to support observations, and clarity and accuracy in their posters or presentations (see Rubric for Group Presentations).