poeexperiments-blog

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Organic waste vs plastic (one to two-month experiment)

While chemists might consider plastics organic substances based on their composition of carbon, nitrogen, oxygen and sulfur, they are anything but organic in terms of the environment. Organic and biodegradable waste eventually turn into dirt and add nutrients to the soil. Inorganic waste, including conventional plastics, does not do this, requiring either recycling or disposal by incineration. However, if plastic is left to the elements in an attempt to compost it, it will eventually break down into tiny bits that infiltrate every part of the environment, causing dangerous and toxic effects to both plants and animals.

In an effort to reduce landfills and garbage in general, composting food waste and other biodegradable waste products is important. Food rots, naturally decomposing back into the environment to become nutrients for other plants to grow.  Additionally, other biodegradable products can decompose as well, including some types of food containers, bags, and packaging materials. All of these objects are made up of different materials so might vary in the time it takes them to decompose. In this experiment, you will learn how to compost, what things decompose and what things do not.

Materials

Compostable or biodegradable products – food such as apple slices, carrots, lettuce, a piece of bread, a granola bar, etc – cardboard pieces – plastic spoon/fork/knife or other plastic products

Synthetic string or yarn

Composting materials

Soil

A large plastic bin

Prepare your test products and line them up on a table or the ground. They should all be roughly the same size if possible, for easier comparison.

Cut a piece of string or yarn that is about twice as long as the height of the compost bin for each test object. Tightly and securely tie a string around each test item.

To prepare your compost bin, add in three to four inch alternating layers of (1) dry leaves, shredded newspaper, crushed egg shells; (2) dead plants, used tea bags, coffee grounds, moist leaves, grass cuttings; (3) moist soil (You can spray with water from a spray bottle if needed).

When you have filled the bin about half full, start including your test products spread throughout the bin so none are touching. Hang the strings over the bin’s side so you can see them. You can use different color strings for each product or tie a note to the end of the string to keep track of which string is tied to which product.

Continue adding alternating layers until the bin is full.

Mix the compost weekly, using a small shovel. Be sure to move material from the bottom of the bin to the top and break up any clumps. You can carefully dig up your test products and examine them but be sure to bury them back in the compost afterward.

Continue weekly mixing and monitoring for about four to six weeks. Some products give estimates for how long they need to be composted to decompose, so plan on timing the experiment to suit. Carefully dig up all of your test products and examine them. Did they decompose? What do they look like?

Side-by-side experiment on composting vs landfills:

Most garbage, including compostable and biodegradable waste, ends up in landfills. However, not everything decomposes as it should in a landfill, taking exponential amounts of time longer than it should. In a typical compost bin, vegetables will take one to four weeks to decompose. If left in the middle of a landfill, the same vegetables might not decompose at all! Landfills are so tightly packed, there is no way for oxygen, dirt, water, or microorganisms to access biodegradable products. In addition, anaerobic conditions cause methane production that is then emitted into the atmosphere. Methane is a greenhouse gas 25 times more potent than carbon dioxide…

To explore this phenomenon, set some of your test products aside. Place these items and some of each of your three compost layers used in the bin into individual sealable plastic bags so that no air can enter. Push the air out, seal the bags and keep them next to the bin without opening for the duration of the experiment. When you dig up the test products in the bin, take these products out of their bags and compare the difference. Did they decompose?

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Pine cone weather station

Want to predict the weather? Ask a pine cone! Pine cones open and close their scales depending on the humidity to help seed dispersal. In dry weather, pine cones open up so wind can catch and carry the seeds, allowing them to be dispersed far away from the original tree so more trees can grow. When the humidity rises and rain is likely, pine cones close to prevent the seeds from escaping. Wet seeds can become waterlogged and cannot travel far. This means seeds will try to grow too close to the original tree and have to fight for resources and sunlight.

Easy weather station: You can place two or more pine cones outside in a protected area where you can watch them change over days or weeks. You will see them open on sunny, dry days and close on wet, rainy days.

Science experiment to measure humidity based on movement of a pine cone’s scales:

Materials

a pine cone

a small box or other container

marker

a piece of paper

tape

 Put your pine cone in a small open box, where you can easily observe it.

Tape a piece of paper to the back of the box behind your pine cone.

Choose a pine cone scale near the top of the pine cone to monitor and color its tip with a marker.

Use the marker to draw a line on the paper behind the pine cone where your colored scale is located as a starting or reference position on day 1.

Place the pine cone outside in the shade where it will not be disturbed.

On day 2, examine the pine cone and check the position of your colored scale. If the humidity has changed, you will see that the scale has moved. Mark its new position with the date.

As the weather changes, continue marking the movement of the pine cone scale each day. As the weather gets wet, you will notice the scale movement closing. As the weather dries out, you will observe the scales reopening.

How does this work? It is all about the structure of the pine cone's scales. In high humidity, the outer side of the scale absorbs moisture, causing the cells expand and bend the scale inwards to shut the pine cone. When the air is dry, these outer cells lose water and shrink, bending the scale outwards to open the pine cone and release the seeds.

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Leaf Science

Most leaves are green but can change colors in the fall. Green leaves contain green chlorophyll, which is essential for photosynthesis. Leaves also contain carotenoids - yellow, orange - and anthocyanins - red. Chlorophyll usually covers these other pigments, except when seasons change and causes chlorophyll to break down in fall. Pick a set of green leaves. Can you find the hidden colors and predict what color the leaves will be in the fall?

Materials

Green leaves from different trees (Try collecting leaves from trees that change to bright colors in fall)

Beaker or drinking glass

Isopropyl (rubbing) alcohol

Plastic wrap

Chromatography or filter paper (coffee filters will work)

Pencil

Leaves from each type of tree should be tested separately so you can compare colors from the different trees.

Tear the leaves into small pieces and place them in a beaker or glass.

Add just enough rubbing alcohol to cover the leaves, then cover the beaker with plastic wrap so the alcohol won’t evaporate.

Place the beaker in a bowl of hot tap water for 30 minutes, or until the alcohol turns green as the chlorophyll pigments from the leaves are absorbed.

Cut a half inch wide strip of filter paper and tape it to a pencil so it hangs down. Hold the pencil over the beaker so the filter paper just touches the alcohol and pigment mixture.

Watch as the mixture slowly travels up the filter paper. Wait for 30-75 minutes for the colors to separate as smaller pigments travel faster. What colors do you see?

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DNA extraction experiment

DNA is in every cell of every living thing. It is the instructions for how we develop and function, and what dictates our unique characteristics.

All living organisms have DNA (deoxyribonucleic acid) in every single cell. People, trees, butterflies, bears, bacteria and more all develop based on instructions provided in their DNA. DNA in humans can differ about 0.1%, meaning all humans share about 99.9% of the same DNA. Our similarity to mice is about 85%, to fruit flies is about 61%, and to bananas is about 60%. Why study DNA? Genetics studies look at how DNA instructs your body to function properly or how to make medicines that affect disease.

Scientists extract DNA from cells using specialized kits, but you can do it at home as well. This experiment outlines how to extract DNA from strawberries using household chemicals. Why strawberries? Each strawberry cell has eight copies of their genome (humans have two), giving them a lot of DNA per cell and making the DNA easier for us to see.

Materials

Rubbing alcohol (to cause the DNA to precipitate out since DNA is not soluble in isopropyl alcohol, especially when the alcohol is ice cold)

Salt (to release the DNA strands by breaking up protein chains that hold nucleic acids together, and to gather and clump the DNA strands, making it easier to see)

Water

Dishwashing liquid (to cause the cells to break, or lyse, so that the DNA is released into solution)

Cheesecloth

Funnel

Tall glass

Three strawberries

Resealable plastic bag

Bamboo skewer or toothpicks

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Chill the rubbing alcohol in the freezer for later.

Make the extraction liquid: Mix 1/2 teaspoon of salt, 1/3 cup of water and one tablespoon of dishwashing liquid in a glass or small bowl and set aside.

Line the funnel with cheesecloth and place onto the top of the tall drinking glass (alternatively you can put the cheesecloth over the glass as well, you just need to be careful pouring in the strawberry mixture).

Remove and discard the green tops from the strawberries, put the strawberries into a resealable plastic sandwich bag and push out all the extra air. Seal the bag tightly. Squeeze and smash the strawberries for two minutes.

Add three tablespoons of the extraction liquid to the strawberries in the bag. Push out all the extra air and reseal the bag. Squeeze the strawberry mixture with your fingers for one minute.

Pour the strawberry mixture from the bag into the funnel. Let it drip through the cheesecloth and into the tall glass until there is only wet pulp left in the funnel.

Take the funnel and cheesecloth off of the glass and discard.

Tilt the jar and very slowly pour up to ½ cup rubbing alcohol down its side until the alcohol has formed about a one-inch-deep layer on top of the strawberry liquid. (You may not need all the alcohol to form the one-inch layer. Do not let the strawberry liquid and alcohol mix.)

Look in between the strawberry layer and the alcohol layer. The strawberry DNA will appear as gooey clear/white stringy stuff.

Dip the bamboo skewer or toothpick into the glass where the strawberry liquid and alcohol layers meet and then pull up the skewer with real strands of strawberry DNA. A single strand of DNA is extremely small, too small to see with the naked eye, but because the DNA clumps together, you can see how much of it three strawberries have when all of their octoploid cells are combined. Remember, each strawberry has a lot of cells!

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Oil spill clean up

Oil spills are an obvious and extreme environmental issue. Learning why these spills are so dangerous and how we can (or cannot) clean these messes demonstrates the enormity of this problem to the environment.

Fill a large, high-walled pan with water.

Optional: add in clay “land” around the edges.

Mix in blue or green food coloring – observe how the food coloring instantly mixes with the water.

Add in one or more floating animal toys (to mimic water-dependent animals such as fish, birds, ducks, etc.)

Drop oil, olive oil or canola oil works, into the pan, trying to avoid the floating animals. What happens to the oil? Does it mix with the water? Does it create pools on the surface? What happens to the animals?

Choose a number of absorbent materials – cheesecloth, paper towel, wash cloth, sponge – plus other cleaning options – spoon, detergent, straw.

Experiment with how each material absorbs any or all of the oil. Which works best? Which does not work?

While working to clean up the oil spill, observe where the oil moves. Does it cover the animals? Does it migrate to the “shore”? Does the oil spread throughout the water pan?

Oil spills are very difficult to clean. Not only is oil not soluble in water, it tends to migrate quickly, covering animals and shorelines. Oil covered animals cannot fly, cannot breathe, and have trouble moving. Plants covered in oil are suffocated and die. Oil spills infiltrate the immediate environment and travel to other areas. The goal of this experiment is to show just how wide-reaching an oil spill can be and how hard they are to solve.