TITLE:  Desert Adaptations - Water

AUTHOR:  Steve Lay, Brown/Hill (Redmond)

GRADE LEVEL/SUBJECT:  4-12; science, biology

OVERVIEW:  Students will experiment with methods of water
conservation by desert plants and animals.

PURPOSE:  When studying adaptations of plants and animals
for life in a desert environment, many concepts remain very
abstract without first-hand experience.  Since it is not
practical, in most cases, to take students out in the desert
and leave them, this hands-on activity is the next best
thing.

OBJECTIVES:
  1.  Students will observe a model situation and make
      inferences about real organisms.
  2.  Students will measure using a balance and record data.
  3.  Students will describe and communicate observations
      relating to specialized organisms and interaction with
      a dry environment.

RESOURCES/MATERIALS:  Sponges, water, balance scale and
example profiles of desert plants and animals

ACTIVITIES AND PROCEDURES:
  Working individually or in small groups, students will be
given a small sponge, saturated with water.  It will be
explained to them that this represents a desert animal 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.  Their "creature"
must be in the open for at least four hours during that time
to feed.

  To measure the beginning moisture content each student or
group will weigh their sponge.  They will then plan a
strategy and write it down along with predictions of what
will happen.  During the experiment time period they will
make and record observations.  At the end of the allotted
time they will again weigh their sponges, record weights,
compare with previous weights and make inferences about the
results in relation to real organisms.  A control sponge
should be left in the open over the entire for comparisons.

  When all is completed, individuals or groups will share
their experiments and results with the entire class.
Afterward conduct a class discussion of methods, results and
how it relates to adaptations for desert survival in real
organisms.

TYING IT ALL TOGETHER:  Students may be asked to invent an
animal or plant perfectly suited for survival in a desert
environment.  They must draw or build this organism and
explain how it is perfectly suited either in writing or an
oral presentation.