What's the Relationship?

Students analyze pairs of organisms and decide what type of ecological relationship they have. Examples include competition, predation, parasitism, commensalism, and mutualism.

This activity is very flexible. It includes plenty of examples that you can distribute throughout your class. It is not the intention to have every student work with every example. Rather, through sharing and whole-class discussion, students can learn from each other and thus gain exposure to all the relationship types.

1. Prep: Make single-sided copies of the EcoDuo cards and Inference Cards, and cut them apart.
2. Decide how many EcoDuo cards you want each student or group to work with, and distribute the cards.
   1. Students at the same table should work on non-overlapping sets of cards.
   2. If students are working with more than one card, make sure the cards show different types of relationships.
   3. Some examples may be more challenging. These are marked in the answer key with an asterisk (*).
3. Choose one example and use it to demonstrate how to fill in an Inference Card.
   1. If students struggle with question 1 (interdependence level), these questions can help:
      • Can the organism live with a different partner?
      • What does it need the partner for?
      • How important is the partner for helping the organism live and reproduce?
   2. In question 3, students choose a confidence level (1 low to 4 high) to acknowledge their uncertainty. Challenging choices are great discussion generators!
4. Work through a sharing activity below or make up your own. Sharing is a great way to stimulate discussion, and the strategies can be used in combination:
   1. Class Inference Chart. To stimulate and organize discussion, make a blank chart based on the Summary Table in the key. Students record their own inferences and add the inferences of their classmates. A chart is included in several of the ideas below.
   2. Skits. Students take turns acting out EcoDuos for the class. The class comes to a consensus about the type of relationship depicted. Or students could mark their inferences on a chart after each skit and discuss after all the skits are complete.
   3. Gallery Walk. Set up areas around the classroom for each relationship type. Students post their EcoDuo cards and filled-in Inference Cards in the appropriate area. Then they wander and record the inferences for all the posted examples, paying close attention to the defenses and confidence levels on the posted cards. The class discusses any disagreements about the inferences and comes to a consensus.
   4. Relationship Groupings. Students gather by the type of relationship inferred. They discuss similarities and differences between examples of that type.
   5. Jigsaw. Similar relationship groups meet as above, then go back to their original teams to share what they learned.
   6. Card Stacks. Larger groups of students gather and sort the Inference Cards into stacks. They discuss similarities and differences.

• Within ecosystems, organisms of different species depend on one another.
• Interactions between organisms may be predatory, competitive, or mutually beneficial.
• Organisms engage in behaviors that increase their odds of reproduction.

60 minutes

Copies

EcoDuo Cards (pdf)
Inference Cards (pdf)

• Which relationships did you have a hard time identifying? Why was that?
• How does the relationship help or harm each organism’s chances of reproducing?
• What are some similarities and differences between different types of relationships?
• If there’s a change to the environment, how might the relationship change?