Bringing in the Pond with iMovie


Unit of Practice #1: Constructing Food Webs for Pond Ecosystems

Title: Constructing Food Webs for Pond Ecosystems
This unit teaches younger elementary children about predator and prey relationships in pond ecosystems. The activities suggested can be done at a live pond site or can be facilitated through the streaming iMovie referenced below. Invitation: Most children like frogs but there are many other animals and plants required to sustain an ecosystem in which frogs can thrive. What do frogs eat? What other kinds of animals live in the local pond?

Unit details
Subject: Science
Learning levels: Primary
Author:  Randy Yerrick

Detailed standards
Students will identify different animals present at the pond by their physical appearance, sounds or evidence of their recent presence (e.g. foot prints).
Students will construct a food web demonstrating the predatory relationships for all animals observed in the pond.
Students will describe which animals are plant eaters (herbivores) and which are predator meat eaters (carnivores) based upon their observed behavior (hunting) or physical features (teeth).
Students will predict which animals are missing from the food web that were not observed but are necessary to sustain balance in the ecosystem (e.g.: larvae which small fish may prey upon).

Data gathering and observations are best when viewed directly at the pond site. However, due to constraints of achieving permission for all students to attend a pond site for issues of location or sanitation, a trip to the pond may be prohibitive. This iMovie has worked well to invite students "into" the pond ecosystem.

Part 1
Students engage in constructing a KWL chart, brainstorming what each student knows about pond habitats.

Part 2
Students will collect evidence of the different plants and animals at the pond. Each plant and animal should be documented on indes cards that will later be shared and displayed with other members of the class. "Evidence cards" will contain the description of the plant or animal and what is known about it. For example, some animals, like frogs will be observed hunting insects while others we can only identify by their tracks or calls. For students who are unable to view a pond directly, the iMovie is useful for data gathering purposes. Students should be encouraged to use it in a variety of ways (e.g.: watching it with their eyes closed and listening carefully for other evidence or cropping and zooming a frame for a closer look).

Animal: Frog
Evidence: Observed directly
Appearance: Green, smooth, wet, brown spots
Food: Bugs Habitat: Swims in water
Predator: Birds and local cats
Other special characteristics: Has 2 teeth in jaw to hold onto prey. Good swimmer and jumper. Could hold breath for over 15 minutes (We timed him!)

Animal: Raccoon
Evidence: Not observed. We identified footprints like tiny hands in the mud.
Appearance: Mammal, mask, ringed tail. F
ood: Small clams
Habitat: Walks on land
Predator: Local snow lynx, bobcats, people.
Other special characteristics: Teacher told us that raccoons always wash their food before they eat. Not because they are clean animals but because they have no saliva glands.

Animal: Crickets
Evidence: Not observed. We identified them by their chirping sound.
Appearance: Not sure
Food: We think they eat plants but we don't know which ones. We will look this up.
Habitat: Likes to hide under leaves and rocks.
Predator: Reptiles and amphibians (lizards, turtles, frogs) and birds (robins, sparrows).
Other special characteristics: High pitched chirping. We have heard that their chirping increases with temperature. We need to experiment to check this out in our classroom.

Part 3
Once all the students have completed filling out their allotments of cards and made other observations at the site, the students return to classroom to compile all that they have found. Once the final cards are approved by the teacher with "known" information that the class deems appropriate, the cards are posted on the bulletin board and pieces of yarn connect each card with its predator or prey. For example, a piece of yarn would connect the cricket and the frog because the frog ate the cricket.

Part 4
Students will re-examine their constructed map and consider questions like: What animals on our chart have no observed food source? What part of the map may be missing that may account for these animals' food? What would be the effect of taking one of these animals or plants out of the food web? Which animals would be affected and which would not?

Part 5 (optional)
Students can be encouraged to collect evidence from another habitat (e.g.: pond, desert, playground) using iMovie or other media and tools. Comparisons can be made between the two food webs.

It is especially crucial that the teacher assist in the sharing of "known" evidence about the pond. It is an opportunity for the group to discuss and share personal information that was not directly observed or to challenge accepted myths with collected evidence. The teacher assists with filling in the blanks on the evidence cards, encouraging students to guess when necessary and confirm when possible their evidence through text resources in the classroom. All of the evidence is re-presented to the class a final time to assure there is consensus on the evidence gathered. Students are encouraged to corroborate or refute evidence during this time. The process of constructing a food web can also be completed also with the software Inspiration which makes excellent concept maps, webs, and mind maps.

The accuracy of each of their evidence cards and the students' corraboration or refutation in the discussion should serve as the primary source of individual students' understanding. Students in small groups can be responsible for certain organisms portrayed on the board and receive group grades for their contributions. In addition students' written stories or journal entries can be collected on such topics as "If you were a frog in the pond what would an average day be like? What would you eat? What animals would you avoid? When would you eat? If there were no more mosquitoes available to eat, what would you do?"

iMovie, digital camera, computer, age appropriate reference books, Inspiration (optional)

See also: Main page for Pond iMovie | Pond UOP #1 | Pond UOP #2 | Pond UOP #3 | Pond UOP #4

For more information, please contact Randy Yerrick at