Exploring Ecosystems

Students study ecosystems and keystone species by focusing on one of the most famous denizens of the Mojave Desert, the giant yucca or Joshua tree.

Unit Overview

Through readings, activities and discussions, students study ecosystems and keystone species by focusing on one of the most famous denizens of the Mojave Desert, the giant yucca or Joshua tree. Teddy and his friends take a field trip to Joshua Tree National Park where their guide, Katherine, explains the threats facing Joshua trees– climate change, wildfires and human encroachment. Students also learn about their cultural significance, why it is important to care about preserving them and steps they can take to safeguard biodiversity.   


  • Grade 3
  • Grade 4
  • Grade 5

Lesson Type

In-class or online lesson

Environmental Topics

Biodiversity, Climate Change, Disasters and Conflicts, Ecosystems, Environmental Justice, Resource Conservation, Sustainable Human Development

Environmental Literacy Core Principles

For a summary of the environmental literacy principles and concepts embedded in this lesson series, please visit Green Guardians Environmental Literacy Core Principles.


ELA: RL.3.1 RL.3.2 RL.3.4 RL.3.7 W.3.1 W.3.4 W.3.5 W.3.7 SL.3.1 SL.3.2 SL.3.3 SL.3.6 RL.4.1 RL.4.2 RL.4.4 RL.4.7 W.4.1 W.4.2 W.4.4 W.4.5 W.4.7 SL.4.1 SL.4.2 SL.4.3 SL.4.5 RL.5.1 RL.5.2 RL.5.4 RL.5.6 RL.5.7 W.5.1 W.5.2 W.5.4 W.5.5 W.5.7 SL.5.1 SL.5.2 SL.5.3 SL.5.4 SL.5.5
History Social-Science: HSS-3.1.1, HSS-3.2.2, HSS-3.4.2, HSS-3.5.1, HSS-4.1.3
Science: 3-LS2-1, 3-LS4-3, 3-LS4-4, 3-ESS3-1, 5-LS2-1, 5-ESS3-1


Teacher Guide

This project may easily be extended into optional family discussions and activities around ecosystems, keystone species, endangered species, invasive species and natural vs human-made climate change. To facilitate this engagement, a family guide (in English and Spanish) has been created which teachers may choose to forward to interested parents and guardians.

Family Guide (English)


Three lessons of 30-40 minutes each and a project.

Lesson 1: What is a Joshua Tree?

Through a story and related activities, students follow Teddy and his friends as they explore ecosystems. Sparked by a news report about illegal destruction of 36 Joshua trees, they get busy searching for more information about the Joshua tree ecosystem in the Mojave Desert.

Lesson 2: A Keystone Species

The story continues as students tour the Joshua Tree National Park with Teddy and his friends. Katherine, the park guide, explains that far from being a wasteland, the desert is full of life. The children learn that Joshua trees are a keystone species but that they also depend on a number of environmental factors for survival. Katherine also shares the diverse ecosystem services provided by Joshua trees.

Lesson Materials

Lesson 3: Preserving Ecosystems  

In the third lesson, students explore threats to the Joshua tree ecosystem: natural disasters, invasive species, reproduction issues, climate change and global warming. They discuss the fire at Cima Dome that destroyed 25% of the Joshua trees in the Mojave Preserve as a case in point. While the situation appears bleak, Katherine ends the tour on a high note with a video that details restoration efforts in the Cima Dome area.

Lesson Materials

Project: My Ecosystem Stewardship Project

Students are invited to become ecosystem stewards. They will research a fragile ecosystem in their local area, make an ecosystem stewardship pledge, and take action to help conserve and restore the ecosystem.

Lesson Materials

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