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Sample Lessons
If you have not reviewed the 4-H
Science Inquiry Model, please
do so before coaching learners in the following lessons.
1. What can
we learn about water at the Pond?
Background
The chemical formula of a water molecule is
H20. This means there are two atoms of hydrogen attached to
one atom of oxygen.
The hydrogen and oxygen in the molecule are attached to each
other by very strong bonds called covalent bonds. There are
also weaker bonds between the oxygen and hydrogen of adjacent
water
molecules. This loose arrangement of molecules gives water
its fluid nature and other remarkable properties.
When water freezes at 32° Fahrenheit (F)
or 0° Celsius (C), it changes from liquid to a solid. Water
boils at 212 F or 100 C.
Learners probably know that when water boils,
it produces steam. In the process of evaporation, the warmed
water is changed from
a liquid to an invisible gas called water vapor. As the water
warms, its molecules move further apart from each other. Another
way to say this is the water becomes less dense. When water
vapor condenses to liquid water, it becomes more dense. The
water cycle
is the process of liquid water changing to a gas and then
back to liquid water.
2. The water
detective
Background
Before leading this lesson obtain information from your local
water utility about where and how drinking water is delivered
to homes in your community. Some private
homes may be supplied by wells for drinking water, gardens, or livestock.
3. What can we learn about plants
at the pond?
Background
The earliest scientific classification (taxonomic)
system was a two-kingdom system: one kingdom was plants, the
second kingdom
was animals. Today, the most commonly used scientific taxonomic
system includes not just two but six kingdoms. These are animal,
plant (plantae), fungi, protists (Protista), eubacteria, and
archaebacteria.
A Kingdom is the first taxonomic category. It contains the largest
number of members. Organisms are classified into a particular
kingdom based on shared characteristics including cell type,
ability to make food, and whether they are single-celled or many-celled.
Plants are many-celled organisms. Their cell
walls are composed primarily of cellulose. The cells contain
green chlorophyll and
yellow-red carotenoid pigments. Most plants have recognizable
root and/or leaf structures, and they store starch as food.
HOwever, within the Kingdom Plantae there are many diver species
that
have interesting adaptations to various habitats on Earth.
Algae may seem like the most obvious plant
to study in a pond or other aquatic environment. However, algae
are not really plants!
The are members of a plantlike group called protists. The belong
to the Kingdom Protista, which was added to the classification
system in the 1970s. Protists are organisms that live in moist
or wet habitats. They may be single- or may-celled. Some contain
chlorophyll and make their own food, others do not.
4. What can we learn about invertebrates
at the pond?
Background
Invertebrates are animals that do not have a
backbone. About 97 percent of all animals on Earth are invertebrates.
The lessons in this Unit focus on aquatic
larvae and nymphs of insects and spiders in the Phylum Arthropod,
and
snails and slugs in the Phylum Mollusk. In addition to these,
there are many other kinds of invertebrates you can study in
the classroom. You can get butterflies (larvae to adult), composting
red worms, beetles, crickets, and snails in kits that include
information, equipment, food and the live invertebrates. You
can buy these kits from biological supply companies (see Appendix
IV). They offer almost endless opportunities for learners to
design inquiry investigations. The 4-H Entomology Manual (4-H
3221) has additional information on insect growth and metamorphosis
to assist in the discussions in this lesson.
5. What can we learn about fish at
the pond?
Background
Fish are vertebrates that live in water without
breathing air from the tmosphere. Vertebrates are animals with
a backbone. Fish are the oldest of all animals with a backbone.
Most fish are covered with scales or plates.
The scales are covered with a slimy mucus that lubricates the
fish's body and protects it from infection. A fish's scales
get longer as it grows. This creates annual growth rings on
the
scales that can be used to estimate the fish's age.
Fins are thin membranes supported by bonelike
rays. All fins are used for balance, and some have additional
functions. The pectoral fins help a fish stay in one place
or allow for lateral and vertical movements. The caudal fin
provides the primary power that moves a fish through the water.
Fish absorb oxygen from the water through
membranes on the gills. Water enters the fish's mouth, passes
over the
gills, and exits the body at the gill opening. The delicate
gill filaments are covered by a bony protective flap called
the operculum
The lateral line runs lengthwise down each side
of a fish. It's a system of openings or pores connected to sensory
canals that are extremely sensitive to water currents and vibrations.
Fish who live in fresh water and fish who
live in salt water face different challenges in maintaining
a proper
balance of salts and water in their bodies. Ocean water has
a higher concentration of salts than the blood of marine bony
fishes. Ocean
fish need mechanisms to remove excess salt from their bodies
while maintaining their internal fluid levels. Marine fish
move large quantities of water through their bodies. The excess
salts
are removed by the kidneys and by special cells in the gills.
A freshwater fish's blood has a higher concentrations
of salts than the surrounding water. In fresh water, the process
of osmosis draws water into the fish and removes salts from the
body. To maintain balance, the specialized kidneys of freshwater
fish pump out excess water as a dilute urine. Their gills contain
salt-absorbing cells that move salt into the fish's blood.
Salmon live in both salt water and freshwater
at different times in their life cycles. Pacific salmon move
between freshwater and saltwater environments as juveniles
migrating to the ocean and as adults returning to their natal
stream. On these migrations, salmon pause in the estuaries
of their parent watershed to allow time for their bodies to
make
the necessary physiological changes.
Fish species have developed different body,
fin, and tail shapes; mouth types; colors; and methods of reproduction
that allow them to survive in different aquatic environments.
A fish's habitat includes the food it eats, where it finds
shelter from predators, and the quality of the water it lives
in. Some of the factors that affect water quality are temperature,
level (amount) of dissolved oxygen and pH, and turbidity caused
by sediment load (silt) and other particulates.
6. What can we
learn about interdependence at the pond?
Background
In this lesson, learners attempt to answer
a predetermined Natural Resource Management Question: "Should
we introduce mosquito fish (Gambusia) into the habitat area
pond?"
To design scientific inquiries to answer the Management Question,
it will be helpful for learners to know more about interdependence.
Learner teams create models involving the
biotic and abiotic parts of a stream environment and depict
energy flow
in a food chain and and then a web pattern. (Remind learners
of the food chain and food web they created in the What's in
a Stream lesson). Then, team design experiments that they can
conduct in a mini-aquaria to determine whether mosquito fish
would be beneficial to the habitat area pond.
Learners should not let the predetermined
Management Question restrict their creativity. There are
many different scientific
inquiries that learners can perform to help answer this question.
7. What's soil got to do with it?
Background
This lesson will introduce learners to some
of the characteristics
of soil and how these characteristics affect wetland function. Review with learners
what they have been taught so far.
Learners have been taught about the water cycle and watersheds.
They know that water is stored in lakes and
wetlands. They know that wetlands can be an important source
of ground water recharge as water percolates down through the
soil.
However, lakes and wetlands could not exist
to store water
where soils are very sandy. A sandy soil’s texture does not allow it
to hold water at the surface. The exception to this is sandy soil in estuaries
and coastal areas where water is located in low lying pockets at the water
table. Sandy soils may have a rapid percolation rate that allows quick recharge
of ground water supplies; yet in these same soils, water may move so
rapidly that plants are not allowed to take up the water they need to thrive.
Soils may be classified by the sizes of their
mineral grains into
four groups: sandy, silty, loamy, or clay. For simplicity we will look at only
sand, silt, and clay. Sand has the largest size particles; they can be seen
by the naked eye. Clay particles are very fine. They are extremely small and
can be seen only with very high-powered microscopes. Silt is in between. Most
soils are a combination of some percentage each of sand, silt, and clay. Soil
scientists can be very precise about soil texture. For instance a “sandy
clay loam” soil contains 25% clay, 20% silt, and 55% sand. In the Flower
Pot activity, leaders will ask learners to “become” the components
of this type of soil! Soil particle size distribution is responsible for the
texture of a soil and its percolation rate.
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