Energy Sciences

Background Knowledge

To ultimately understand the role of the Sun and how it is important to our lives, we must explore how the Sun transfers energy to other objects. When referring to plants, this process is known as photosynthesis. The type of energy used in photosynthesis is chemical but the transfer from the sun is through radiation. Some may ask themselves, so there are different forms of energy? Absolutely! We will take a deeper look into the most common forms of energy, and then analyze the form of Light Energy or Radiation as it relates to photosynthesis.

To appreciate the benefits and effects of energy, it is important for teachers to also know the foundation of energy and its various forms. First, there must always be a balance of energy and it is neither lost nor created. We call this balance Energy Conservation. We often think of the word conserve as "saving" or cutting back. For example, a common phrase is "Conserve Energy by turning off the lights when you are not using them." However, in scientific terms, conservation has a slightly different meaning. Energy can change from one form to another or transfer from one object to another. It can change, but cannot be created or destroyed. ¹

Both students and teachers often have several misconceptions about energy. This unit will help clarify those misconceptions and allow you to go beyond your own thinking by thinking outside of the box. One common misconception is that energy only occurs in moving objects. This is not true and to help clarify this misconception we will take a look at examples of both moving objects and objects at rest.

The two most common forms of energy are: Kinetic and Potential. Energy is the ability to do work. One way we can explain this difference to our students is by having them engage in a simple demonstration using a pencil. Have students place the pencil at the edge of their desk. The energy inside the pencil is Potential or stored energy. Then have them push the pencil off their desk and onto the floor. The movement within the pencil is Kinetic energy or energy in motion. If you place the pencil higher off the desk, it has more potential energy. The higher it is from the ground, the further it could fall which gives it more potential energy. ²

Bill Nye, the Science Guy, also shows an excellent demonstration to help explain the conservation of energy using a pendulum. By pulling the pendulum back, you are giving it potential energy. When you release it, it now has more kinetic energy that it gained during the movement. If you stand in the same spot when you pull back and release, the pendulum will never hit you because kinetic energy can never be greater than potential energy. ³

Forms of Energy

- Radiant Energy (*Light Energy) This type of energyis electromagnetic energy that travels in transverse waves. Radiant energy includes visible light, x-rays, gamma rays and radio waves. Light is one type of radiant energy. Sunshine is also radiant energy, which provides the fuel and warmth that make life on Earth possible. (*Starting with the sun is a great way to show students how it affects all parts of our lives.)

- Thermal Energy (*Heat): This type of energy is the vibration and movement of the atoms and molecules within substances. As an object is heated up, its atoms and molecules move and collide faster. For example, if you heat up liquid glue, the molecules begin to move faster causing it to run out of the tube at a faster rate.

- Sound Energy: This type of energy moves through substances in compression waves. Sound is produced when a force hits or causes an object to vibrate — the energy is transferred through the substance in a wave.

- Electrical Energy: This type of energy is transferred by tiny charged particles called electrons, typically moving through a wire. Lightning is an example of electrical energy in nature.

- Chemical Energy: This type of energy is energy stored in the bonds of atoms and molecules. Chemical energy is converted to thermal energy when we burn wood in a fireplace, when we cook or when we burn gasoline in a car's engine. Chemical energy also occurs in plants when they make their own food through photosynthesis.

- Spring Energy: This is a type of potential energy. A good example to use is a Slinky to show how the spring does the opposite motion of the force being applied to it. For example, when you pull on it and apply force, it will push or spring back in the opposite direction.

Although this list is not a comprehensive list or all inclusive, it illustrates the most common forms of energy we face on a daily basis. Let's reference back to the first form, Radiant Energy. This form is vital to the process of photosynthesis, which must have participation from the Sun in order to take place. It seems as if the Sun definitely is a major contributor to all forms of energy and critical to our survival.

Photosynthesis

How do plants breathe and make their own food?

When teaching the section on plants for this unit, it is important for you to understand how photosynthesis occurs. Photosynthesis can be divided into two parts semantically, with photo meaning "light" and synthesis meaning "putting together." Both words are Greek and when combined together produce a meaning: "using light to put things together." Another common misconception is that plants "eat" food. This is not correct because plants are unique organisms that make their own food. In relating this to students, I will begin by asking them what some of their favorite foods are or where their food comes from using a picture or diagram. Common responses for young children are often: "My mom made it," "It came from the grocery store," "What do you mean……it came out of that box?!" Further pose the questions to get them thinking about the process of their food. Where did it come from before it arrived at the grocery store? What products were used to make your food? For example, if their favorite food is pizza, there are a lot of ingredients used to make pizza. Just starting with the dough, the main ingredient is grain. Where does grain come from? It must be planted, grown and harvested. When it is planted, what does it need to grow? Bingo! The SUN! Everything ultimately reverts back to the sun.

The sun transfers light energy to the leaves of a plant into tiny cells that contain chloroplasts. In the cell of the plant, light combines with carbon dioxide from the air and water from the roots to start the Light Reaction of Photosynthesis. Depending on the age of your students and their developmental level, you could then discuss the Dark Reaction of Photosynthesis or the "Calvin Cycle."

The purpose of the Calvin Cycle is to take energy from the Light Reaction and start Carbon Fixation, which is the process of adding more carbons. ⁴ Once this is combined using a chemical reaction with the light and water, sugar or glucose is formed. Oxygen is then released into the atmosphere, giving us what we need to breathe and survive.

If we didn't have carbon dioxide, we wouldn't be a warm planet; we would be cold like the moon. If we had too much carbon dioxide, we would be like Venus, which is a really hot planet. Plants keep our atmosphere from getting too much carbon dioxide and heating up by turning a lot of it into biomass and oxygen. To help students understand the difference between carbon dioxide and oxygen, explore a simple breathing activity. When we inhale, we are breathing in oxygen. When we exhale we are blowing out carbon dioxide. Give each student a small cup filled with water and a straw. Have them practice blowing through a straw to simulate the carbon dioxide released from our lungs. To extend and make it truly scientific, you can use BTB, a Bromothymol Blue solution to observe the change in colors when our breath reacts with the solution. This change lets us know that carbon dioxide is present. For this simulation, it is best for the teacher to model with the BTB solution and have students practice with water so they don't accidently drink the solution. We are constantly breathing carbon dioxide out and taking in oxygen. But what happens when carbon dioxide increases in the air and plant production decreases? This question could then lead to a discussion of Global Warming and how what we do has an impact on the amount of carbon dioxide put into the atmosphere.

Global Warming

What role does the Sun play?

Global Warming occurs when there is an increase in temperature which in turn causes a climate change. What are the causes of climate change? That issue has been highly debated, but most scientists feel that humans are the main cause in Global Warming due to their increased use of fossil fuels. Imagine our world with one or two people using fossil fuels and driving cars. It wouldn't be detrimental to our environment. However, with over 6 billion people in our world, the use of fossil fuels and release of carbon dioxide is an alarming realization. Decreasing the use of fossil fuels can help keep our Ecosystem balanced. For example, when leaving a room, turn off the lights and any electrical devices not in use. Try to carpool with neighbors when riding to school to reduce the amount of gas emitted from your car each time it is driven. Creating a flow map with students is a useful organizer that may help them understand how humans impact the environment (See Figure 1). Energy from the sun allows plants to help balance this emission of greenhouse gases in the atmosphere.

Fossil Fuels

What role does the Sun play?

There are three major forms of fossil fuels: coal, oil and natural gas. All three were formed many hundreds of millions of years ago before the time of the dinosaurs – hence the name fossil fuels. Long ago, as trees and plants died, they sank to the bottom of the swamps and oceans. They formed layers of a spongy material called peat. Over many hundreds of years, the peat was then covered by sand and clay and other minerals. This turned into a type of rock called sedimentary. More and more rock piled on top of more rock, and it weighed more and more. It began to press down on the peat. The peat was squeezed and squeezed until the water came out of it and it eventually, over millions of years, turned into coal, oil or petroleum, and natural gas. ⁵ If we go back to the first step, the trees and plants died which means they were once alive. What helped the plants survive? Bingo! The Sun! To simulate this process for students you can make dirt cups to show the different layers. Simply get a clear cup and place tiny leaves or grass at the bottom for layer one. Then cover with sand and tiny pebbles for layer 2. Layer 3 will include larger rocks and the last 2 layers will be soil and grass to show the "topsoil." To make this simulation even more interesting, you can substitute the outdoor items for food such as crushed Oreos, graham crackers, etc.

Alternatives to Fossil Fuels: What are other methods we can use to decrease the amount of Carbon Dioxide in our environment?

Solar Energy

There are several pros and cons to the use of Solar Energy. There are three main ways solar energy can be converted for our use including: Photovoltaic, Biofuel, and Heat Engines. ⁶ Start by asking your students if they have ever seen a solar panel on the top of a building. Explain how this process is very similar to the process discussed earlier on how plants use photosynthesis to trap light energy from the sun. Many calculators in the school system also operate on solar power. When you are in a dark room or away from a window source, it makes it difficult to see the numbers on a calculator. However, placing it near light allows it to work with ease. Solar energy is great in the sense that it does not place harmful chemicals into the air. However, a downside to solar energy is that the sun does not shine everyday (cloudy days) and, therefore, it must be stored or combined with an alternate energy source as well. The Photovoltaic process involves the use of solar panels and solar grids. The grids are used to transport energy from the sun that has been converted into electricity. Individual solar cells are arranged in rows and columns to create Photovoltaic Cells (PV Cells). This is an excellent connection to math and 3 ^rd grade students should be very familiar with the use of arrays when referencing multiplication. Ex. 5 solar cells placed horizontally and 3 placed vertically produce a total amount of 15. Place several different sized solar cells and have students calculate the total number of single cells within each PV. Remind students that even though this is an alternate source to fossil fuels, it still requires the use of……..that's right…..THE SUN!

Wind Energy

Wind turbines are beginning to become a common form of energy in certain parts of the world. This type of energy involves kinetic energy of the wind which can be transferred into other forms such as mechanical or electrical. A familiar example for students to see is by using or making a pinwheel. Small turbines make enough energy to power a house. In order for a wind turbine to work efficiently, wind speeds usually must be above 12 to 14 miles per hour. Wind has to be this speed to turn the turbines fast enough to generate electricity. The problem with wind energy, like the sun, is that it is not blowing all the time. Therefore, the best way is to combine it with another source of energy. ⁷

Once students have learned the basic forms of energy, the process of photosynthesis, the role of our Sun in energy transfer and alternative energy sources, they are ready to use that knowledge to take them to the next level. They will explore the positive and negative effects humans have on the environment and what they can do to help.