By Kim Fulton

The main purpose of Invasive Species Dodge Ball is to illustrate how quickly invasive species can change ecosystems forever.  It is also an exciting way to stimulate conversation and interest in a study of ecosystems and invasive species. In British Columbia, where I live, spiny ray fishes such as perch and bass are a threat to our aquatic ecosystems in which salmon and trout thrive. Zebra mussels, quagga mussels, and invasive aquatic plants are current threats to ecosystems. People in areas where perch and bass are popular game fish will want to choose other species.  Asian Carp, goldfish, snakehead fish may be good choices.  However, make sure you choose local invasives to make it relevant for your students. 

Dodge ball is a popular game for many students and there are many variations. But it can become a bit “wild” so before you start, discuss safety, particularly hitting only below the waist. Make sure the class will freeze when you ask them to.

Grade Levels: 4 to adult

Subject areas: Science, Physical Education, Social Studies, Language Arts discussion skills, Math, and Environmental Studies (Integration of subject areas is one cogent way to overcome the time crunch. With a bit of creative planning and using thematic approaches many learning outcomes can be achieved simultaneously.)

Time: 35-60 minutes depending on time available and amount of discussion. This could be part of a larger unit or theme

Location: Soccer Field, Tennis Court, Open Field area, or Gymnasium

Materials: Pylons, hula hoops or gym mats, 10-20 volleyballs, playground balls or any ball with a soft covering.

Procedure:

Lay out the playing area similar to the diagram below.

The safe areas may represent habitat – weed beds or other cover, the outside boundary represents dry land and the center area is where the invasive species (and the balls) “hang out” The native species cannot leave the water area but the invasive species may leave to retrieve a ball. 

Native species are safe in the safe area until the teacher yells “Feeding Time!” They must then move in a clockwise direction to the next safe area. Have all the balls in the center area and select one girl and one boy to be the invasive species. Divide the rest of the students into four equal groups. They are the native species.  Allow the native species to feed a few times moving clockwise from one safe area to the next. 

Then make a big deal of introducing the invasive species to the center circle.  Then yell “feeding time” and the invasive species try to hit the native species below the waist as they move from one safe area to the next.  If hit with a ball, the native species gets a ball and joins the center circle as an invasive species.  This symbolizes the transfer of nutrients to the invasive species. After each “feeding time,” record the # of invasive species for graphing later on.  Invasive species may leave the center circle to retrieve a ball but must return to the centre to throw them.

Follow-Up Discussion:

Stop the game when down to the last few native species. Ask students for modifications to the game that they think might improve it.  Discuss the biology of introducing a species that has not evolved in that ecosystem. There are no natural predators for the invasive species, they out compete the native species for food and habitat, reproduce like crazy and eat the eggs, fry, and adults of the native population.  Discuss ways new species may be introduced into ecosystems.  They may be introduced intentionally or accidentally.  Not all introduced species become invasive but many do because there are no natural controls. 

Prevention is the name of the game with invasive species.  Students can take action by helping educate the public and take personal action to not be part of the problem.  Most students have a natural interest in studying plants and animals by collecting and having them as pets.  It is important that they learn to return samples to the exact spot they got them and not move them around.  It is also important that students understand the difference between pets and wild animals and that wild animals are best studied in the wild.  Many introductions of goldfish, pet rabbits, kittens for example, are from unwanted pets being introduced into natural systems.  Brainstorm ethical, environmental methods of dealing with pets that are no longer wanted. We coined the phrase:

“Wild and free, let it be!”  If it’s a pet look after it!”

Kim Fulton (aka Dr. Fish) is a retired teacher who lives
in Armstrong, British Columbia and works as Educational Facilitator for the Habitat Conservation Trust Fund and Wild BC.