A review of the Xeriscape science curriculum for Middle and High School students

"But there is not enough water", is a cry not often heard in England. However in the southwestern United States, as for increasingly large areas of the world, this is a common lament. Mark Twain once said "Whiskey is for drinking and water is for fighting over." For countries with limited water resources, increasing demands for water from growing populations, coupled with recurrent droughts, have put untenable demands on water resources. International relations become strained when rivers run through several countries and upriver dams limit water to downriver countries. Learning to conserve and use water wisely is an issue for both developing and developed countries. In developed countries, competition is often between industry, tourism and sportsmen, farmers, and cities. A hierarchy of current needs competes with traditional rights.

In New Mexico, as in the rest of the southwest, there is a critical water shortage. The northern half of the state receives about 20 inches of rainfall per year, while the southern half receives less than 7". (England averages 20-130" per year). As a result, governments have to carefully evaluate where water goes and how to optimise use. One area where conservation can be effective is in maintaining landscapes. Many people have moved to the southwest from more mesic areas and install water-guzzling landscapes similar to what they have been used to, rather than adapting their landscapes to a desert ecosystem.

Learning to Xeriscape, A Hands-On, Problem-Solving Curriculum for Middle and High School Students is a book, which I co-wrote. It is published by the New Mexico Office of the State Engineer and is designed to teach students and their families about xeric ecosystems, water conservation and help them to think creatively about possible ways of dealing with these issues in their daily lives. While this is primarily a science curriculum, it also includes projects dealing with politics, social studies, language arts, mathematics and art.

The curriculum can be used in its entirety, as separate chapters, or individual labs or activities can be used to supplement existing science programmes. It is not intended to compete with established all-encompassing science curricula but to complement what is already in place.

What's in a name?

Xeriscape is water-efficient landscaping that is appropriate to the natural environment. The term xeriscape is derived form the Greek word xeros, which means dry. The goal of xeriscaping is to create visually attractive landscapes that use water efficiently. The curriculum in this book is organized according the seven basic principles of xeriscaping that consider the relationships between soil, plants, water and ecosystems: soil characteristics, efficient irrigation, mulching, appropriate turf areas, low water use plants, proper maintenance and good planning and design.

Each chapter is organised around a "Problem to Solve" that requires critical-thinking, decision-making, and problem-solving skills. The students are required to complete the activities in the chapters in order to solve the problem. All of the activities are interdisciplinary and hands-on. For teachers, each chapter includes a discussion of the xeriscape principle, background information on the topic, student handouts and assessments.

The first chapter deals with issues that apply to the world as a whole: distribution and availability of water, types of habitats and the politics of allocation. The first lab gives students a global perspective of water availability, focusing on the fact that most water in the world is unavailable for biological use (ice caps and glaciers are, technically, deserts, because water is locked up as ice and, therefore, is not available for living organisms). The second laboratory asks the questions: What are the habitats in New Mexico and how do rainfall and elevation influence these habitats? This unit also explores the history of New Mexico water and water rights, and studies the acequia system of irrigation in New Mexico communities, which not only regulates water use, but also strongly influences the culture and social life of the community. The final activity examines the politics of water allocation and allows students to assume the role of special interest groups and allocate the state's water.

The second chapter, soils, is typical of the format for the rest of the curriculum. Following teacher's notes on the unit and individual labs, background information is given on soil structure (physical, chemical and biological) and how these can be amended. The problem to solve concerns Andy Devalle's Soil and is presented in the form of a letter:

"Valencia county Extension Agent
1000 Main St. NW, Bldg 16
Los Lunas, NM 87031

Dear County Extension Agent:
I just bought a new house up on the mesa in Los Lunas with beautiful views. I am planning to landscape the whole yard.

I have already put in a small flower garden. However, the soil in this spot is mostly sand and the water runs right through it. Before I landscape the rest of the yard, is there something I can do to improve the soil so that it holds water better?

The letter goes on to say that Andy has enclosed soil samples for analysis. Students are then instructed to "Use the information you have learned from the activities, the handouts and reference books to help Andy Devalle solve his landscape problem. You can give Mr. Devalle a plan that can be accomplished very quickly or a plan that will take him several years to accomplish.

When you have decided on a plan for Mr. Devalle, write him a letter telling him the steps you think he should take to improve his flower garden. Be sure to tell him why you are giving him the advice you are providing. Students also receive a project cover sheet to help them organise the activity, tips for getting started, and teacher-provided soil samples " sent in by Mr. Devalle" that they can test and evaluate, using the knowledge gained from the labs they will do as part of the unit.

The labs in the unit look at soil structure (Soil through the Looking Glass), porosity and water holding capacity (Holes in the Soil), biological activity (Who Lives in Soil?), which soils plants prefer (Best of the Best) and soil amendments (It All Looks Like Dirt to Me!). Each activity has objectives, subject links, time to complete, vocabulary, materials, and advance preparation advice and introduction suggestions. Students are provided with activity procedures and worksheets.

At the end of the curriculum are community outreach activities, a glossary, technical information and suggestions for extending the activities and linking them with national organizations and other schools. Additional resources, grant information and supplemental xeriscape web sites are also given. A CD is included with the binder.

While the curriculum is aimed at Middle and High School students, it could easily be adapted for lower grades and is also highly recommended for alternative education situations such as after school programmes or elective courses. Many of the activities could also be used as general science, art, math and social studies activities.