Activity 3: Species: The Building Blocks of Nature

PDF versions of Activity 3: Species: The Building Blocks of Nature are available in English and Spanish.

Objectives: Kids will learn the definition of a species and ecosystem. They will understand that the trophic chain of an ecosystem is cyclic rather than linear, and that each species of the chain is equally important to the well-being of the entire ecosystem.

Materials: decorated wood or Jenga blocks, trophic chain poster


Have you ever heard of the word species? Yes? What do you think it means? (wait for responses, then explain) A species is a group of animals, insects, or plants that look similar and that can reproduce, or have babies. For example, do you think that a frog and a cat could have a baby? Why not? That’s right, because they’re different species.

What about ecosystem? Has anyone heard of that word? (wait for responses) An ecosystem is a community of species that live in the same place and interact.

Now, species live in ecosystems, right? And in an ecosystem, every species has a job to do. In science, this job is called a niche. (Show them the poster and explain how each species in the ecosystem has a niche and that they are all related)


  • Have wood blocks (Jenga), representing different species of a trophic chain, spread out around table. Have kids start building a tower out of the blocks, telling them that the parts of the chain must go in a certain order. They can find the right order on the trophic chain poster, which will show a cycle.
  • After the trophic “tower” (five levels of Jenga blocks) is complete, have one of the kids pull out a block from one of the higher areas (but not the top) of the tower and ask them to explain what happens to the tower without the block (an ecosystem component is missing).
  • If the tower did not fall with the first block, have another kid pull out another.
  • Repeat until the tower collapses. Explain how every species is important and how, the disappearing of a single species might make the whole ecosystem disappear.
  • Once the tower is collapsed and no longer a trophic chain, have the kids re-construct it in the same order as the first time.

Post-activity discussion questions:

  • Could the tower, or trophic/food chain, stay strong and intact without each and every block?
  • What do you think this represents? (Point them to the trophic chain poster)
  • So, for example, if all of the ____ in this ecosystem die (pick a species in the trophic chain poster and point to it), what happens to all the other species that live there? [Explain that that is the same as removing a whole level in the towers they just built, and that one species’ extinction results in its consumer’s extinction, becoming a cycle that brings down the entire system]
  • Why is it important for every species to stay alive and healthy in this ecosystem?