Experiments

How to Make Compost

Creating the Perfect Compost

A Quick Extension to “How to Make Compost” and “Creating the Perfect Compost”

The Eggs-periment

How to Make Cheese

Color-Changing Carnations

Garbage Grunge

Earthworms: Nature’s Tillers?

Advanced Extension to “Earthworms: Nature’s Tillers”: Earthworm Castings: The Ideal Proportion

Mud Huts: How to Make Heat-retaining Adobe Brick

How to Make Compost (from Heifer’s Global Barnyard series)

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Just like pig manure, compost can improve your garden soil and make your vegetables or flowers grow stronger and healthier. Here’s how you and your family can make some compost:

What you need

• 2-liter soda bottle
• Water spray bottle
• Scissors and plastic wrap
• 2 cups dried leaves
• 1 cup grass clippings
• 1 cup chopped kitchen scraps (no dairy, meat or bones)
• 1 cup garden soil

Directions

• Cut the top off the bottle.
• Pour the ingredients into the bottle.
• Add a little water and mix the ingredients.
• Use plastic wrap to make a top and place the bottle on a sunny window sill.
• Watch your bottle! Water it if it starts to get dry and take the top off if it starts to smell.

Your compost will be ready when it is evenly brown and there are no visible food scraps left. Plant some flowers or a vegetable plant in the compost. It will love the rich soil you’ve created!

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Creating the Perfect Compost (adapted from http://www.epa.gov/epaoswer/osw/kids/pdfs/sciencefair.pdf - Get Free Adobe Acrobat Reader)

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Composting can be a good way for gardeners to reuse food scraps and yard trimmings while making their gardens healthier. In order to work properly, a compost pile needs the right balance of air, moisture, carbon and nitrogen. In this experiment, you can test different types of compost piles to see which kind recycles materials most effectively.

What you need

• 3 2-liter soda bottles
• Water spray bottle
• Scissors and plastic wrap
• 2 cups dried leaves
• 2 cups grass clippings
• 1 cup chopped kitchen scraps (no dairy, meat or bones)
• 1 cup coffee grounds
• 3 cups garden soil

Directions

• Label the bottles 1, 2 and 3.
• Cut the top off each bottle.
• In bottle 1, put 1 cup soil and 2 cups dried leaves (this will be a carbon-rich compost).
• Add a little water and mix the ingredients in bottle 1.
• In bottle 2, put 1 cup soil and 2 cups grass clippings (this will be a nitrogen-rich compost).
• Add a little water and mix the ingredients in bottle 1.
• In bottle 3, put 1 cup soil, 1 cup chopped kitchen scraps and 1 cup coffee grounds (this will be a relatively equal mix of carbon and nitrogen compost).
• Add a little water and mix the ingredients in bottle 3.
• Use plastic wrap to make a top on each bottle and place the bottle on a sunny window sill.
• Watch your bottle! Water it if it starts to get dry and take the top off if it starts to smell.

Make a chart to record your observations. What are the similar and unique characteristics of each bottle? Which one seems to produce the best compost? You can also experiment with different amounts of water, light and air to see how the compost is affected.

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A Quick Extension to “How to Make Compost” and “Creating the Perfect Compost”:
Secrets of Gardening Success (adapted from http://www.epa.gov/epaoswer/osw/kids/pdfs/sciencefair.pdf - Get Free Adobe Acrobat Reader)

Compost can help plants grow by adding important nutrients to the soil. You can test the effectiveness of compost as a soil amendment by planting small potted gardens, adding compost to some and using only soil for others. Fast growing seeds, such as sunflower or bean seeds, will allow you to see results in a matter of days. See for yourself how compost helps plants grow!

What you need

• About 2.5 cups soil
• About 1 cup compost
• 3 small pots
• Sunflower or bean seeds
• Water

Directions

• Label the pots 1, 2 and 3.
• Place 1 cup soil in pot 1.
• Mix ¾ cup soil and ¼ cup compost and place in pot 2.
• Mix ½ cup soil and ½ cup compost and place in pot 3.
• Plant a seed in each pot and water lightly.
• Make sure the pots receive the same amount of moisture and sunlight to control the experiment.

After your plants have grown into small seedlings, you can compare their root structures and stems. Does adding compost to the soil result in healthier, stronger, faster-growing plants? Is there an optimal level of compost to add?

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The Eggs-periment (from Heifer’s Global Barnyard series)

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What do an egg shell and the Capitol building have in common? They both contain the shape of a dome! Domes are strong because they spread weight evenly. To test the strength of an egg and the shape of a dome, try this:

What you need

• 4 eggs
• A towel
• Books

Directions

• Crack each egg in half. Throw out their insides and the pointy half of the shells. You could also make some scrambled eggs if you’d like!
• Place a towel on a flat surface and position the eggs on top to make a square.
• Add books one by one on top of the egg shells so that the weight is distributed evenly.

How many books do you think the eggs can hold before they crack?

Do you think egg shells can protect the insides of an egg?

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How to Make Cheese (from Heifer’s Global Barnyard Series)

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Milk is a wonderful source of protein and calcium. It helps us grow and stay healthy. Cheese, just like yogurt and butter, is made from milk. Here’s how you can make cheese at home:

What you need

• ½ gallon of whole milk
• Medium size pot
• 1/8 cup of white vinegar or lemon juice
• Spaghetti strainer
• Seasoning (garlic powder, dill or oregano)
• Salt

Directions

• Pour the milk into the pot.
• Heat slowly while stirring continuously until the milk boils.
• Turn off the heat, add vinegar or lemon juice and continue to stir for five minutes. You should notice the milk separating into solids and liquid.
• Pour the mixture into a strainer over the sink.
• Once most of the liquid has drained out, salt and season the cheese to taste.

This delicious crumble cheese is best eaten loose over crackers. It will look like cottage cheese.

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Color-Changing Carnations (from Steve Spangler Science; www.stevespanglerscience.com)

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Where does the water go when a plant is watered? In this experiment you will see how and where water is absorbed into a plant.

What you need

• 6 white carnations
• 6 plastic cups 
• Food coloring (red, blue, and green work well) 
• A knife 
• Water

Directions

• Fill each cup half full with water.
• Add about 20-30 drops of food coloring to each cup of water. In this case, more food coloring is better!
• Before placing any of the flowers in the colored water, trim the stem of each flower at an angle to create a fresh cut. 
• Place one freshly cut white carnation in each of the cups of colored water. Make some predictions: Which color will be soaked up first? How long will it take?
• You'll want to check back every few hours to see how things are progressing. It may take as much as 24 hours for the colored water to work its way up to the white petals. 
• At the conclusion of your experiment, remember to examine the whole plant carefully, including the stems, leaves, buds and petals, to find every trace of color.

How does it work?
Most plants "drink" water from the ground through their roots. The water travels up the stem of the plant into the leaves and flowers, where it makes food. When a flower is cut, it no longer has its roots, but the stem of the flower still drinks up the water and provides it to the leaves and flowers.

If the water a plant uses to grow was polluted, would that affect the plant? In what ways?

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Garbage Grunge (from Judy Schneider at Lesson Plans; http://www.lessonplanspage.com/ScienceExWhatGarbageBreaksDownFastestMO68.htm)

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What kinds of garbage break down the fastest, the most and the easiest? When you throw something “away,” does it really go away? Find out the answers with this experiment!

What you need

• A plastic container (like a yogurt cup)

• 3 types of garbage (for example: vegetable peels, egg shells, mushrooms, nut shells, paper, aluminum foil or plastic)

• Soil (from your yard, not potting soil)

Directions

• Fill a plastic container half full of soil.
• Add a little water, but only enough to make the soil wet, not watery.
• Bury three kinds of garbage in the soil, one from each of the sets below:

Set 1
vegetable peelings
bread
food leftovers

Set 2
egg shells
nut shells
paper

Set 3
aluminum foil
plastic
a penny

• Make a list of the garbage and check it every day for changes.
• Be sure the soil stays damp. Add a teaspoon of water each day, if necessary.

Make a chart to record your observations. Which materials break down the fastest, the most and the easiest? Which materials show no signs of breaking down?

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Earthworms: Nature’s Tillers? (from Science Buddies; http://www.sciencebuddies.org/science-fair-projects/project_ideas/PlantBio_p007.shtml?from=Home)

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In this advanced experiment, students can learn more about earthworms. Earthworms act as nature’s plows by incorporating surface plant material into the soil. They play a major role in maintaining soil fertility by recycling nutrients from soil surface residues and sustaining soil structure by providing glue that holds soil particles together. Does the number of worms in the soil affect how fast surface plant material will be incorporated into the soil?

What you need

• Ten-inch diameter clay or plastic pots
• Topsoil 
• Earthworms 
• Grass clippings 
• Metric ruler 
• Kitchen measuring cup

Earthworm treatments
0 worms per pot
10 worms per pot
20 worms per pot
50 worms per pot
100 worms per pot
Five pots per treatment

Directions

• Place the same volume of soil in each pot (there should be 2 inches from the soil surface to the rim of the pot).
• If the soil is dry (does not form a ball when squeezed in your hand) pour tap water (one cup at a time) slowly over the potting soil surface until water drains from the pot. Allow the pot to drain for 2 hours before adding worms. 
• Place the required number of worms per pot in each pot and allow them to work down into the potting soil. 
• Place 2 cups of grass clippings uniformly over the surface of the potting soil in each pot.
• Each week, measure the depth of the grass clippings in each pot and record your findings.

What are the ideal conditions for encouraging earthworms to eat? How does the amount of light, water and heat change the speed with which earthworms decompose organic matter? How does earthworm density change the rate of grass decomposition?

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Advanced Extension to “Earthworms: Nature’s Tillers”:Earthworm Castings:
The Ideal Proportion (from http://www.sciencebuddies.org/science-fair-projects/project_ideas/PlantBio_p002.shtml?from=Home)

In this advanced experiment, students can learn more about how earthworms affect soil fertility. Earthworms play an important role in soil fertility, and they are often used as a quick indicator of soil fertility. What do earthworms do to the soil and do they really help to improve plant growth?

What you need

• Earthworm castings
• Potting soil
• Pots (enough to have 2 pots for each plant variety at each combination of castings to soil)
• Plants (at least three varieties)

Directions

• Prepare the pots with mixtures of earthworm castings and potting soil. You should plan to have at least two pots per plant variety for each mixture of soil and castings. Some possible mixtures of earthworm castings are 0%, 20%, 40%, 60%, 80% and 100%.
• Select plant varieties to be used for the experiment. Remember that you will need at least two tests of each plant with each mixture of castings, so don't select too many different varieties. We suggest using no more than three different plant types to keep the experiment manageable.
• Plant one plant per pot and make sure that you test each plant variety in each mixture of castings.
• Place the pots in locations where they will get equal amounts of light and make sure you provide them with equal amounts of water. 
• At the end of the experiment, photograph each of the plants and examine them for growth.

What is the ideal amount of earthworm castings to use for each plant? How do you know?

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Mud Huts: How to Make Heat-retaining Adobe Brick (from Science Fair Projects: The Environment, by Bob Bonnett and Dan Keene, Sterling Publishers, NY: 1995, pp 72-73)

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In the southwestern US and in Mexico (and in other parts of the world), where there are not many trees, people often build houses out of mud bricks called adobe. Adobe houses are warm in the evening and cool in the daytime. If a mud brick is warmed by the sun, how long will it continue to give off warmth once the sun goes down?

What you need

• Soil
• Water
• Bowl
• Large mixing spoon
• Straw, dry grass or pine needles
• 2 thermometers
• One-pint milk carton
• Clock
• A sunny window
• Pencil and paper

Directions

• Gather some straw. If you do not have straw you can use dry grass, or dry pine needles.
• Put the straw, soil from your yard, and water into a bowl and mix it well.
• Open the top of the empty one-pint milk carton. Pour the mud mixture from the bowl into the milk carton. 
• Make a hole in the mud by pushing a pencil halfway down in the middle of the opening. Loosen the mud around the pencil by moving the pencil in a small circle, and then leave it in the carton. 
• Place the milk carton in a sunny window and leave it there for several days to dry.
• When the brick is firm and dry, take the pencil out of it and peel off the carton. 
• Leave your brick in a sunny window for one more hour. Then, put the brick on a table out of the sunlight.
• Put a thermometer into the hole of the brick. This will measure the temperature inside the brick. 
• Lay another thermometer nearby on the table to measure the temperature of the air outside the brick. 
• Wait a few minutes, and then read and write down the temperatures showing on the thermometer inside and outside of the brick. 
• How long will it take before the thermometer inside the brick is the same temperature as the one outside of it?

Many people around the world use different materials to build their houses. What are some of the advantages to using adobe bricks to build a house? What could be added to the mud mix to make stronger bricks?

Adobe bricks are not used for building in places where there is a lot of rain, or where it is cold. What would happen if adobe bricks froze and thawed a lot? What happens to adobe bricks if they keep getting wet?

What are some other materials that can be used to build houses?

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