Overview & Lesson Sequence

Focus on Standards & Assessment

Materials Needed, Preparation & Planning, Management Strategies

Background Info

Intro Activity
Why Study Populations?

Meet the Aphids

Research Project
Aphid Population Growth

Data Analysis I

Data Analysis II

Optional Activity
The Power of Exponential Growth

References

Glossary

Suppliers

Resource Sheets

Great Gravidity Home

CISEO Home

Materials Needed
See the Plant Propagation and Aphid Rearing sheets for a list of supplies needed to grow the plants and aphid colonies.

For a list of materials needed for each activity, see "Materials Needed" within each activity.

Note
Pea aphids are considered plant pests and should not be released into the wild. At the end of the lesson, all pea plants with pea aphid colonies need to be destroyed. An easy method is to wrap the plants and aphids in a plastic bag and place in the freezer for at least 48 hours.

Preparation and Planning
Sow peas 10-14 days prior to the arrival of aphids. See Plant Propagation for instructions and a list of materials. Plan to have at least three true leaves on each plant before the aphids arrive; this should take approximately 10-14 days depending on the temperature and humidity of your classroom. Plant approximately two pots per student group to ensure that each group has at least one healthy plant for its research project. Sow additional seeds three to seven days prior to the arrival of aphids to ensure a backup supply of plants.

Order aphids two to four weeks before you plan to begin the lesson (see list of suppliers) or collect aphids from the wild and establish them on host plants following aphid rearing instructions. Order at least one aphid colony for each two student groups. Note that aphids do not travel well especially during very hot or cold weather, therefore a shipment may arrive with a few dead aphids. Ordering well in advance allows enough time to establish a healthy culture before you begin the activities.

Decide whether students will construct aphid handling materials, bottle cages. and clip cages, during class time or as homework. These need to be assembled before you begin the activities. See the respective sheets for instructions and a list of materials.

Management Strategies
Depending on class size, assign three or four students to a group. All group members should participate in designing their experiment, setting up the tools and habitats, and collecting data. At the end of each week, spend a few minutes in class discussion during which students compare raw data and make predictions. Discuss any observations or questions they raise.

Note
The success of this lesson depends upon the careful nurturing of live aphids and host plants. Make a visual check of all aphid colonies and plants every day, especially during the first week of the investigation when students are still uncertain about handling live insects. Many aphids will die naturally during the course of the experiment. Have some back-up colonies.