Wow it is Hot! Exploring Water Conservation among
Organisms in Desert Ecosystems
Melissa Kruse
In this lesson, students will explore how animals and plants live in arid desert
ecosystems. Students will experiment with methods of water conservation by desert
plants and animals by designing their own organism, and developing and testing
hypotheses of how well it conserves water.
Keywords
desert, ecosystem, habitat, water conservation, adaptation, inquiry
Grade Level 10, but appropriate for younger students 7-8
Subject
Life Sciences
Duration
2 class periods to include a supplemental lecture
Overview
This lesson is intended to introduce students to desert ecosystems and how organisms
conserve water through an inquiry approach. In the lesson, students will observe a
model situation and make inferences about real organisms and their ability to conserve
water in a dry environment. Students will develop hypotheses and interpret the results
of their observations. Students will measure using a balance, record data, and
communicate ideas in a written and oral format. Although this lesson was designed to
be implemented during an ecology unit it is also well suited to talk about other concepts
such as adaptation, natural selection, and global climate change.
Standards
NATIONAL SCIENCE EDUCATION STANDARDS
Content Standards: 5 – 8
Content Standard A
Abilities necessary to do scientific inquiry; understandings about scientific
inquiry
Content Standard C
Structure and function in living systems; regulation and behavior
ARIZONA STATE STANDARDS
Eighth Grade
Strand 1: Inquiry Process
Concept 1: Observations, Questions, and Hypotheses
PO 3. Generate a hypothesis that can be tested.
Concept 2: Scientific Testing (Investigating and Modeling)
PO 5. Keep a record of observations, notes, sketches, questions, and
ideas using tools such as written and/or computer logs.
Concept 3: Analysis and Conclusions
PO 1. Analyze data obtained in a scientific investigation to identify trends.
PO 2. Form a logical argument about a correlation between variables or
sequence of events.
PO 5. Explain how evidence supports the validity and reliability of a
conclusion.
Concept 4: Communication
PO 1. Communicate the results of an investigation.
PO 3. Present analyses and conclusions in clear, concise formats.
PO 4. Write clear, step-by-step instructions for conducting investigations
or operating equipment (without the use of personal pronouns).
PO 5. Communicate the results and conclusion of the investigation.
Strand 4: Life Science
Concept 1: Structure and Function in Living Systems
PO 6. Relate structures of living organisms to their functions.
Concept 3: Populations of Organisms in an Ecosystem
PO 2. Explain how organisms obtain and use resource to develop and
thrive
Materials
Sponges of various kinds
Water
Balance scale
Natural materials for students to design their habitat including fabric, leather, paper
bags, potted plants, grass clippings, sand, leaves, gravel, etc.
Procedures
1. Students should begin by brainstorming as a class about what resources are
essential for survival and what would be limited in desert ecosystems. This
brainstorming should include their ideas of how organisms get and conserve
these resources.
2. Working individually or in small groups, students will be shown all of the materials
including the sponges. Explain to the students that the sponges will be saturated
and represent desert organisms with a limited amount of available water. Their
job is to conserve that water. Over a 24 hour period they are to take care of their
"creature" in a manner that will best achieve this goal using only natural
materials.
3. Students must plan a strategy and write it down. The plan should include a
description of the creature’s habitat, physiological characteristics, and feeding
behavior (see # 5 below). Students are instructed to use any of the natural
materials provided to design their habitat. Encourage them to think of unique
ideas and provide very few limitations. Some of these materials relate to
physiological characteristics such as the shape, size, and pore size of the
sponge. The written plan must include hypotheses of what they think will
happen.
4. After writing their plan, students build their habitat and select their sponge. They
should weigh the saturated sponge with the balance scale and record their data.
2
5. Their "creature" must be in the open for at least two hours total representing the
time their creature feeds. The written plan should include the strategy of the
creature’s feeding behavior. For example, does it come out for 2 hours at a time
or shorter periods of time, several times a day? During this time the sponge
must be taken out of the designed habitat and left in the open. It works to have
the students return to the classroom to put their creature back in their habitat
after school, at lunch, or before school or a combination. A secondary goal of
this project can be to teach learning responsibility by instructing students that it is
their duty to coordinate this part of the project.
6. To measure the beginning moisture content each student or group will weigh
their sponge and again after the 24 hour period. During the experiment time
period they will make and record observations. At the end of the allotted time
they will again weigh their sponges and record weights. They should compare
with previous weights and the weight of a control creature that was left in the
open for 24 hours. They can graph this data.
7. When all is completed, individuals or groups will share their experiments and
results with the entire class in a discussion format. They should complete a
written discussion of their results and interpretations about the survival of their
creature. They should make inferences about the results in relation to real
organisms.
Assessment
Students should then be able to “invent” an animal or plant perfectly suited for survival
in a desert environment. They should be given additional information delivered in a
lecture or video about desert organisms and adaptations. They should draw or make a
model this organism and habitat. Most importantly the students should be able to
explain how it is perfectly suited to conserve water in a desert environment in a written
format or an oral presentation.
3