Lesson 3
How Can People Conserve Resoures
Fast Fact
Water, Water Growing plants in water - hydroponics - has a long history. Scientists
think the ancient Babylonians sometimes grew plants this way, without soil. If
people ever live on other planets, hydroponics will likely be the best way for them
to grow vegetables. In the Investigate, you'll find oui for yourself how to grow
plants in water.
Growing Plants in Water
Materials
 scissors
 dry plant food
 liter bottle
 plastic food container with lid
 measuring spoon
 radish seeds
 soft, absorbent cloth
 water
Procedure
1. Carefully use the scissors to cut a slit in the lid of the food container. Then cut a
hole in the lid, large enough to pour water through.
2. Cut a rectangle of cloth that will fit through the slit and touch the bottom of the
container when the lid is in place. The cloth should be long enough to allow about 2
cm of it to lie on top of the lid.
3. Push the cut cloth through the slit in the lid, leaving the end of the cloth on top.
4. Follow the instructions on the package of plant food to make 1 L of plant-food
solution. Half-fill the container with the solution. Snap the lid closed on the
container.
5. Place the seeds on the cloth.
6. Place the container in a sunny window. Add more plant food as necessary to keep
the cloth moist.
Draw Conclusions
1. Why do you need to use plant food to grow seeds without soil?
2. Inquiry Skill Draw a conclusion about why this method of growing plants would be
useful in desert areas.
Investigate Further
Plan and conduct a simple investigation for growing large plants without soil.
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Reading in Science
SCIENCE CONCEPTS
 what conservation is
 how people can help in conservation efforts
VOCABULARY conservation p. 83
READING FOCUS SKILL
CAUSE AND EFFECT Look for ways that conservation decreases pollution.
cause
effect
The Three R's: Reduce, Reuse, Recycle
When you leave a room and turn out the lights, you're saving natural resources. When
you wash out a cottage cheese container and use it again, you're saving resources.
Every time you throw a newspaper in the recycling bin, you're also saving
resources. These actions are all examples of conservation.
Cut 5 minutes off your shower and save 20 gallons.
Reuse
Think twice before you throw out that milk container! Could you use it for another
purpose?
Reduce
Communities with a shortage of water or energy may require people to use less
water or energy.
Recycle
Recycling a ton of newspaper saves 17 trees from being cut down.
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Conservation is preserving or protecting natural resources. The actions described in the
photos are examples of the three R's—reduce, reuse, and recycle. The three R's are
effective ways to conserve natural resources. When you reduce, you cut down on
the amount of resources used. Appliances such as clothes dryers, water heaters, air
conditioners, and lamps use a lot of electricity. When you use appliances less, the
need for energy resources such as coal goes down. This also means less pollution
caused by burning fuels.
When you reuse, you use items again that might have been thrown out. For example, if
you reuse plastic food containers, fewer resources are needed to make new
containers.
Reusing often means using items for new purposes. For example, you can wash out
milk cartons and juice bottles and use them as planters or bird feeders. As a result,
the cartons and bottles are saved from the landfill and you have items you can use.
Sometimes you can't use items anymore. You might give those items, such as toys
and clothes you've outgrown, to a resale shop. Then other people can reuse them.
Reusing items saves resources, reduces pollution, and saves space in landfills.
When you recycle, items are changed into a form that can be used again. Many
resources can be conserved by recycling. For example, aluminum, glass, and paper
can be ground up or melted down and used to make new glass, aluminum, and
paper products. When people recycle, energy is saved, too. And as with reducing
and reusing, recycling saves resources and reduces pollution
Math in Science
Interpret Data
---see graph
Insta-Lab
Search and Reuse
There may be things in your classroom that you've never thought of reusing. Look
around the room, and identify an item you might throw out. Then think of a way
the item can be reused. How can reusing the item help the environment?
CAUSE AND EFFECT What are some of the effects of reusing items instead of
throwing them out?
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Soil Conservation
A necessary resource for growing crops is soil. How can this resource be protected?
Reducing, reusing, and recycling are general ways to conserve resources, but there
are some specific methods of soil conservation.
When farmers of long ago cleared fields to plant crops, they pulled out trees and native
plants that kept the soil in place. Sometimes wind and water carried away the
unprotected soil and left the land unsuitable for farming.
Farmers had to learn ways to protect the soil. One method farmers use to keep soil in
place is contour plowing. This is the planting of crops along the curves of sloping
land, not down the slopes. With this type of plowing, water cannot flow quickly
downhill and carry soil with it.
In areas where the land is very steep, farmers use another method to help conserve soil.
They build up the soil to form flat places, or terraces. These can look like a series
of steps going up a hill. Crops are then planted on the
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flat areas. The result is that the soil is protected from being carried away by water
running down the steep slopes.
Crop rotation is another way farmers conserve soil. Crop rotation is the changing of
planted crops from year to year. When the same crop is planted year after year, the
soil can lose important nutrients, such as nitrogen. These nutrients are often
replaced by using chemical fertilizers. But by rotating crops, farmers can build up
the soil's nutrients naturally. For example, corn takes nitrogen from the soil.
Alfalfa, if grown after the corn, adds nitrogen to the soil. Avoiding chemicals in
this way reduces the risk of land and water pollution.
A method called intercropping keeps soil healthy by reducing the need for pesticides.
When farmers intercrop, they plant different crops near each other. This keeps
some harmful insects from spreading, since many insects eat only one kind of crop.
One practice, called intercropping, involves alternating different crops. A tall crop
is planted next to a low crop that grows well in the shade.
Farmers lost millions of acres of soil in the 1930s. Government scientists then
taught farmers contour plowing as a way to keep soil in place.
Crop rotation helps control pests. The pests die when the plants they eat are not
being grown.
CAUSE AND EFFECT What is an effect of contour planting?
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Water Conservation
If you're in the middle of a heavy rainstorm, the idea that water needs to be conserved
may sound strange. For much of the country, though, fresh water is a precious
resource.
Drought is a constant threat in the western United States. The population there is also
growing. This has led many to believe that soon there will not be enough water for
everyone.
As a result, governments, farmers, and others have begun to look for ways to conserve
water. Some farmers have started growing crops that don't need much water. Others
who once sprayed water onto their crops are now using dripirrigation. This method
slowly drips water onto the ground. Less water is lost to evaporation.
Homeowners can conserve water by using different plants in their yards. Lawns require
a huge amount of water, which isn't available in some areas. To conserve water,
homeowners can plant native grasses, flowering plants, and shrubs that don't
require as much water.
People can learn to conserve water in other ways, too. They can take shorter showers.
They can remember not to leave faucets running. What else can you think of that
would help conserve water?
CAUSE AND EFFECT What has caused farmers to use drip irrigation?
Drip irrigation uses hoses with tiny holes that slowly release water.
Landscapes that conserve water can include flowering plants and shrubs as well as
native plants.
Reading Review
1. CAUSE AND EFFECT Draw and complete this graphic organizer.
-see chart
2. SUMMARIZE Write three sentences that summarize this lesson.
3. DRAW CONCLUSIONS Which of the three R's—reduce, reuse, recycle—applies
to landscapes that conserve water? Explain.
4. VOCABULARY Use the term conservation to explain how to save resources at
home.
Test Prep
5. Critical Thinking How can a farmer and a factory owner conserve water?
6. Which of the following can conserve energy?
A. crop rotation
B. intercropping
C. drip irrigation
D. recycling newspaper
Writing
Persuasive Writing
Write a letter to local government officials to persuade them to find ways of conserving
energy resources.
Math
Display Data
Each day for a week, weigh the trash your class produces. At the end of the week, make
a bar graph that shows the weight of the trash by day.
Health
Air Quality
Reducing, reusing, and recycling mean less pollution. Research the health problems
caused by air pollution, and find out what you can do to protect yourself from air
pollution.
For more links and activities, go to www.hspscience.com
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