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Around the World: The Invasive Species Challenge

Originally appears in the Fall 2014 issue

The reality of invasive species can be difficult for some students to grasp.  Their idea of an invasive species can range from the simplistic, “no big deal, it’s just a weed,” to the extreme; a rampaging, alien invader who has come to wreak havoc on our landscape. They also may believe that invasive species are only a problem in other places. Teachers must put the seriousness of the threat into perspective, and balance it with positive actions the students can take in their daily life. This outdoor activity is designed to foster team-building skills, and educate participants about the threat that invasive species pose to human health, the economy and biological stability of local ecosystems. This game also challenges students to think about the ways that invasive species are spread through human activities and how they can become proactive in helping to reduce the spread of these destructive organisms.

In the Invasive Species Challenge, students are tasked to work as a team to “clean up” various invasive species in their local environment by removing colored balls from a playing field and placing them in the appropriately colored bin as fast as possible. Various rules restrict how they can interact with the balls so the students must make group decisions about tool selection and leadership to formulate an effective plan. Several trials can be conducted which encourages the students to reconfigure their problem solving techniques each time and makes them anxious to try again. At the end of the exercise, the students will have an understanding of invasive species that threaten their own ecosystem, plus a feeling of empowerment from “beating” the example species in the game.

Grade Levels: 6-12

Time: 45 minutes to 60 minutes


  • Stopwatch
  • 4 different color plastic bins
  • Bag of plastic colored balls with at least 5 different colors (balls approx. 3” diameter)
  • 2 small plastic 1 gallon white buckets with handles
  • 3 plastic sport cones
  • 2 garbage pickers (pinchers)
  • 3 pieces of ½” thick rope approx. 4 ft in length
  • List of the rules to read to the players


  • A flat, dry, grassy area is perfect to use as the playing field, approximately 40ft x 40ft square in size.
  • Place a colored bin (red, green, blue and orange – we use 18 gallon plastic containers) in each corner of the playing field. Each colored bin represents a country.  The flag and name of that country is posted on the outside of the bin (facing the inside of the playing field).
  • Scatter colored balls across the playing field. Place the balls randomly within the borders of the colored bins.


  1. Students are broken into small groups (6-15 students per team). This activity can be run as a station for a larger group of students doing an extended program with one team at a time or multiple teams can compete against each other at the same time with duplicate sets of materials. If the teams are competing at different times, be sure that the tools and playing field are kept hidden so that one team does not have an unfair advantage over the others in terms of planning time. The goal of each team is to get the fastest time.
  1. Instructor will ask students to define an invasive species and ask them to name a few that they know are causing problems in their local environment. (Do this out of sight from the playing field so they are not distracted.) According to the US Environmental Protection Agency, an invasive species is a plant or animal that is non-native (or alien) to an ecosystem, and whose introduction is likely to cause economic, human health, or environmental damage in that ecosystem. Students frequently cite invasive species they have seen on TV which is a good starting point, but we try to connect it back to organisms present in our own ecosystem as much as possible to emphasize that this is a local issue and not “someone else’s problem.”
  1. Select four invasive species that are currently prevalent in your area to discuss. Students will learn what country each invasive originated from, how they spread and why they are a problem in the native ecosystem. Examples of species that are common in our region of western Pennsylvania are Japanese knotweed, zebra mussels, emerald ash borer and the fungus that attacked the American chestnut tree. If possible, show the students a specimen of the invasive species so they can identify it in the future and begin to recognize its prevalence in your community.
  1. After introducing the invasive species, lead them out to the playing field. The red, blue, green and orange colored balls each represent an invasive species. The native species are represented by the other colors of balls. Tell students they will be acting as a group of scientists that must return each invasive species to its original homeland (corresponding color bins) as quickly as possible using only the tools provided.
  1. Lay out all the tools on the ground in front of the team so they can see them. The tools are: 2 small plastic white buckets with handles, 3 plastic sport cones, 2 garbage pickers (pinchers) and 3 pieces of thick 4 ft. rope. Teams will be given time to examine the tools and come up with a plan before the clock starts for the trial. We usually give them a 5-7 minute planning session. Once the group hears the rules and they agree on a plan, then the clock will start.
  1. Read the following rules to the group before starting the clock. The rules are:
  • Players cannot touch any of the invasive species (red, blue, orange, green balls) or the buckets with their body parts (skin).
  • Players cannot touch or move the native species (other colored balls) at any time or they will be penalized.
  • Players are allowed to touch the ropes, pinchers and the cones.
  • Players cannot take their clothes, hats or shoes off and use them as tools.
  • Teams must decide as a group which tools to use and which tools not to use.
  • Everyone must be assisting the team in some way (cheering doesn’t count).
  • No pinching each other with the pinchers.
  • Teams will be penalized for infractions of rules (for example: touching or moving a native species, misplacing balls into wrong bins or using bare hands to move balls)
    • Rule Clarification: We do allow the use of clothing and shoes as worn by the students when the rules are read to them. For example, a student can pull their hand inside a jacket and touch the balls with the jacket, but they cannot remove the jacket to use as a separate tool.  Also, students can kick the balls to a location with their shoes, but they can’t pick up balls with a shoe they have taken off.
  1. Once the team is ready, have them line up along one side of the playing field. Yell “go” and start the stopwatch. The clock will not stop until all species have been returned to their respective countries.
  1. Discussion Points – After the first trial, instructors should ask the students to think about the following:
  • Contamination: Are you spreading the invasive species to other countries inadvertently? In other words, ask how many students visited more than one country during the trial or touched more than one type of invasive species. Why might this be a problem? Recommend that they assign certain people to certain colors to avoid spreading the invasives to other countries.
  • Equal Color Distribution: Ask the students to look at the color distribution among the balls. Is it equal? When we conduct this activity, we use an unequal distribution of colors on purpose. (Usually 25 blue balls, 20 green balls, 5 orange and 5 red balls). Usually they do not notice this initially, it causes them to rethink their approach. (Sometimes it may take some gentle guidance from an instructor to make them realize that they don’t need a large group to collect the 5 red balls, and to rethink their team assignments.)
  • Get Creative: To make it challenging, we use small pieces of orange plastic mesh fencing material (we call it fungus) in place of the orange balls. This forces them to think about the tools most appropriate for the job during the planning stage. The garbage pickers come in handy with this one!
  1. Deduct any penalties by adding time to their score. We usually let each group try at least 3 times or more if time allows – students will beg us for more time. (If you have numerous classes participating in this challenge, have them come up with a team name. They are always curious to know which team of their peers has the best time.
  2. The tools and rules used in this game are based on items that we had easily on hand. Be creative and introduce new tools or variations in the rules to suit your situation.
  3. Have fun and good luck!


To view the photo-rich magazine version, click here.


April Claus has been the Director of Environmental Education at Fern Hollow Nature Center since 2005, and also serves as the naturalist for Sewickley Heights Borough Park in Sewickley, Pennslyvania. April has a strong love of herpetology and enjoys educating local school children, scouts and other community groups about these misunderstood animals. Susie Moffett has been an Environmental Educator at Fern Hollow for 5 years. After years of doing research in genetics, Susie loves to teach kids about the wonders of science in our natural world. Stacey Widenhofer has been an Environmental Educator at Fern Hollow for 7 years.  She loves to teach the preschool and elementary students and get them excited about the little things, especially birds.