Dec 16, 2009

"Evergreens" keep most of their leaves during the winter. They have special leaves, resistant to cold and moisture loss. Some, like pine and fir trees, have long thin needles. Others, like holly, have broad leaves with tough, waxy surfaces. On very cold, dry days, these leaves sometimes curl up to reduce their exposed surface. Evergreens may continue to photosynthesize during the winter as long as they get enough water, but the reactions occur more slowly at colder temperatures.

During summer days, leaves make more glucose than the plant needs for energy and growth. The excess is turned into starch and stored until needed. As the daylight gets shorter in the autumn, plants begin to shut down their food production.

Many changes occur in the leaves of deciduous trees before they finally fall from the branch. The leaf has actually been preparing for autumn since it started to grow in the spring. At the base of each leaf is a special layer of cells called the "abscission" or separation layer. All summer, small tubes which pass through this layer carry water into the leaf, and food back to the tree. In the fall, the cells of the abscission layer begin to swell and form a cork-like material, reducing and finally cutting off flow between leaf and tree. Glucose and waste products are trapped in the leaf. Without fresh water to renew it, chlorophyll begins to disappear.

The bright red and purple colors come from anthocyanin (an-thuh-'si-uh-nuhn) pigments. These are potent antioxidents common in many plants; for example, beets, red apples, purple grapes (and red wine), and flowers like violets and hyacinths. In some leaves, like maple leaves, these pigments are formed in the autumn from trapped glucose. Why would a plant use energy to make these red pigments, when the leaves will soon fall off? Some scientists think that the anthocyanins help the trees keep their leaves a bit longer. The pigments protect the leaves from the sun, and lower their freezing point, giving some frost protection. The leaves remain on the tree longer, and more of the sugars, nitrogen and other valuable substances can be removed before the leaves fall. Another possible reason has been proposed: when the leaves decay, the anthocyanins seep into the ground and prevent other plant species from growing in the spring.

HOW PLANTS PREPARE FOR WINTER

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HOW PLANTS PREPARE FOR WINTER

All summer, with the long hours of sunlight and a good supply of liquid water, plants are busy making and storing food, and growing. But what about wintertime? The days are much shorter, and water is hard to get. Plants have found many different ways to get through the harsh days of winter.

Some plants, including many garden flowers, are called "annuals," which means they complete their life cycle in one growing season. They die when winter comes, but their seeds remain, ready to sprout again in the spring. "Perennials" live for more than two years. This category includes trees and shrubs, as well as herbaceous plants with soft, fleshy stems. When winter comes, the woody parts of trees and shrubs can survive the cold. The above ground parts of herbaceous plants (leaves, stalks) will die off, but underground parts (roots, bulbs) will remain alive. In the winter, plants rest and live off stored food until spring.

As plants grow, they shed older leaves and grow new ones. This is important because the leaves become damaged over time by insects, disease and weather. The shedding and replacement continues all the time. In addition, deciduous trees, like maples, oaks and elms, shed all their leaves in the fall in preparation for winter.

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WHY DO LEAVES CHANGE COLOR IN THE FALL?

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WHY DO LEAVES CHANGE COLOR IN THE FALL?

Plants make their own food. They take water from the ground through their roots. They take a gas called carbon dioxide from the air. They turn water and carbon dioxide into food and oxygen. Oxygen is a gas in the air that we need to breathe.
Plants make their food using sunlight and something called chlorophyll. Chlorophyll gives leaves their green color.

Winter days are short and dry. Many plants stop making food in the fall. The chlorophyll goes away. Then we can see orange and yellow colors. These colors were in the leaves all summer, but the green covered them up.

Some leaves turn red. This color is made in the fall, from food trapped in the leaves. Brown colors are also made in the fall. They come from wastes left in the leaves.

Why Do Leaves Change Color in the Fall?

We all enjoy the colors of autumn leaves. Did you ever wonder how and why a fall leaf changes color? Why a maple leaf turns bright red? Where do the yellows and oranges come from? To answer those questions, we first have to understand what leaves are and what they do.

Leaves are nature's food factories. Plants take water from the ground through their roots. They take a gas called carbon dioxide from the air. Plants use sunlight to turn water and carbon dioxide into oxygen and glucose. Oxygen is a gas in the air that we need to breathe. Glucose is a kind of sugar. Plants use glucose as food for energy and as a building block for growing. The way plants turn water and carbon dioxide into oxygen and sugar is called photosynthesis. That means "putting together with light." A chemical called chlorophyll helps make photosynthesis happen. Chlorophyll is what gives plants their green color.

As summer ends and autumn comes, the days get shorter and shorter. This is how the trees "know" to begin getting ready for winter.

During winter, there is not enough light or water for photosynthesis. The trees will rest, and live off the food they stored during the summer. They begin to shut down their food-making factories. The green chlorophyll disappears from the leaves. As the bright green fades away, we begin to see yellow and orange colors. Small amounts of these colors have been in the leaves all along. We just can't see them in the summer, because they are covered up by the green chlorophyll.

The bright reds and purples we see in leaves are made mostly in the fall. In some trees, like maples, glucose is trapped in the leaves after photosynthesis stops. Sunlight and the cool nights of autumn cause the leaves turn this glucose into a red color. The brown color of trees like oaks is made from wastes left in the leaves.

It is the combination of all these things that make the beautiful colors we enjoy in the fall.

Dec 14, 2009

* Some of those kids (maybe yours someday) qualify for the international competition at the annual Intel International Science and Engineering Fair. Here the level of cash prizes is significant. In addition, those whose projects qualify for international competitions are judged by the best in the world: top scientists and people from industry. Imagine your child having his or her project judged by a Nobel Laureate. These kinds of things do immeasurable good for the confidence of the student and certainly encourage them further in all of their activities.

These are just of few of the many different benefits of science fair projects. Even if you, as a parent, secretly dread the idea, your help and encouragement with this endeavor will provide life-long advantages for your children.

* A science fair project is an experience that can be challenging and self-validating. Many students actually do important research and discover previously unknown facts.

* Many science fairs offer cash prizes, which can be a significant incentive for some people. They also help open the doors of academic opportunity for students. Winners at regional fairs receive recognition for their work, and gain the right to participate at state-level and higher-level competitions.

* Participating in science fair projects help develop a feeling of confidence and competence among students, and fosters a spirit of scientific inquiry. Projects usually involve scientific questions that the student is interested in, and a specific topic they have chosen for themselves. Participants must research their question, learn and apply the scientific method to create a valid experiment, and think about the meaning of their results. Some kids get so immersed in their project that they forget about other factors like prizes or the fact that they are actually learning new skills. Science fairs are also a way for students to demonstrate motivation, self-learning, critical thinking, ethics and other important skills and traits.

* A science fair project is an activity that integrates almost every skill or art children have been taught. Students must learn how to apply their existing abilities to new areas, as well as learn many new skills. A science fair project can involve reading, logical thinking, writing, grammar and spelling, math, statistics and data analysis, computer science, and graphic arts, as well as scientific methodology. If a student participates in a formal competition, then they will also practice public speaking, and learn how to explain and defend their work in front of a panel of judges.

Science Fair Projects 5 Valuable Benefits For Your Child

Science fair projects can be really exciting, especially now with all the opportunities the internet gives us. Most kids know how to use a computer for fun and spend, on an average, five hours a week surfing the net. As parents, we would like to encourage them to use some of their computer time for schoolwork and educational projects. And researching scientific ideas and the scientific method are certainly a good use of their time. But in addition, there are many other great reasons for encouraging your children to do science fair projects.

THE FINAL PRESENTATION

Are you able to answer the judges' questions knowledgeably and confidently? Be sure to use your display while the judges talk to you. It isn't just a backdrop, it's a visual aid to the information that you've worked so hard to obtain. Make sure that you explain every element of the board and make sure that the board looks as professional as possible.

The final judging is mostly subjective. While the judges are looking for a few specific things, the way that you represent yourself and your project, and the way that your display board looks can make the difference between leaving a poor impression, and impressing the judges with your award winning science fair project.

SKILLS

Are you knowledgeable about the experiment itself--did you design it and perform the experiments? Having a good command of the technical aspects of your project reflects very well on you. Know what you're talking about, and know your experimental data, but also know the ins and outs of the experimental apparatus.

DATA

Was your data collection scientifically professional? Be sure to use a journal to record data from the experiment. This demonstrates organization. Did you repeat the experiment? Repetition lends much more reliability to your data. Repeat it if you can.

INTERPRETATION

Is your use of tables and graphs helpful to the judges in understanding your data? Did you use the tables and graphs correctly and collect enough data to reach a reliable conclusion? Make sure that you are confident in your final numbers. Science is all about proof.

Winning science fair projects What are judges looking for?

To produce an award-winning science fair project, you need to understand how the judges select a science fair winner. The point scoring system for your science fair may differ from others -- there is no standardized point system -- but generally speaking, science fair judges have a similar method of judging. That is, they start with a neutral score, not good or bad, and then depending on the performance of the presenter, points can be added or subtracted from the final score. If you do the following, there's a good chance to improve your score.

OBJECTIVES

Is your project full of original and well-thought-out ideas? Were you clear in describing the problem you were researching? Be sure you know your material, especially the content of your final report. Was your science fair project too easy? A difficult or advanced project can make a difference in how the judges evaluate it, and whether or not it becomes a winning science fair project.

Science Fair Report & Presentation

Whether your teacher requires an in-class science fair report & presentation of your science project, or its just for the judges at the fair, you will probably have to give an oral presentation on the content of your science project. There may or may not be a time limit, but even if there isn't, it's important to keep your presentation short and to-the-point. Be sure that your science fair report touches on all of the elements of your project, including but not limited to the points of the Scientific Method.

Be sure to practice. Giving an oral presentation, and talking to the judges at the fair who may be teachers from other schools whom you've never met before, could end up being the hardest part of the science project. Practice will give you the confidence you need to sound like an authority in your area of research, and that's something that the judges like to hear. Points at a science fair are awarded for your ability to discuss the project clearly and to explain each stage of your research and every step of your experiment. The judges will ask you questions, and so practice will really help. Try to have someone ask you questions about your project. It might make you think about things that you haven't thought of before. An important thing to remember is to never make up answers to difficult questions. Instead of admitting that you don't know, tell the judges that you didn't discover the answer to that question during your research, and then present other, relevant information.

Finally, your appearance may also affect the way that the judges view you. A professional appearance will reflect well on you and your project. You are not only trying to look professional, but you are trying to make your project look like the result of thoughtful, mature, and professional scientific research.

In summary, it's important that you have a professional-looking, well-organized science fair display board to make a good impression on the judges. It is also important that you appear relaxed and knowledgable while presenting your science fair report.

Science Fair Display Boards

So how should you set up your science fair display?

Let's look at the basics. A science fair display should consist of a back board, sometimes sold specifically as a science fair display board, a project report, graphs and charts, and some representation of your experiment. Of course it would be great if you could bring your science fair experiment into the fair, but if it's too big, or if it was strictly observational, consider bringing in photographs or a part of the experimental apparatus. Some people even bring in a small television and show a video presentation of their science fair experiment. Whatever you choose, your science fair display has to represent your project in such a way that it holds the interest of the judges--so be creative, but keep it simple.

The size and shape of science fair display boards can vary, so be sure to check the rules for your particular science fair. Some maximum sizes for most science fairs are 48 inches wide, 30 inches deep, and 108 inches from the floor. Generally speaking, no matter the size, a traditional science fair board is divided into three sections: the main center section, and two "wings" which are folded toward the front. These science fair boards can be made from scratch from heavy cardboard or wood, or can be ordered inexpensively over the internet.

Now, think about the things you'll want to attach to the science fair display board. Some science fairs, and most teachers, have rules or guidelines for what should be attached to the science fair board. These might include cut-out lines of text which detail your original question, which will be your project topic, your hypothesis, results, conclusions, and other information including charts and graphs. The title of your project should always go on the center panel at the top of your science fair display board and be large enough so that people can see it from about three feet away. The other pieces of text can be smaller, and should be placed in a logical order. In other words, let the judges read your hypothesis before they read your conclusions. Several years ago, it was common to use stenciled or cut-out letters mounted on the science fair display board, but now that most students have access to word processors and printers, it is more common for these lines of text to be printed in large letters. There is no rule about this, but be aware that looks do matter at the science fair, and a word printed on a laser printer looks a lot better than one drawn and colored with a marker.

It's most important that you have a science fair display board that the judges will remember in a good way, and not just because it used bright colors and big letters. You want the science fair board to look professional and well-organized so that the judges aren't distracted. Make it look professional, and the judges will treat your project professionally.

Preparing a science fair display board & science fair report to highlight your project results

This is it - the big day is finally here! Everyone will be looking at your science fair display board, reading your science fair report, and listening to your presentation, which must all present your project in the best possible way.

All of your work must be summarized here. This is your chance to show the world the information that you've learned from your experiment. Your science fair display and report are the ways that the science fair judges will remember your project when they make their decision. It's important that your scientific work was good, but that's not everything....

When you design your science fair experiment, you have to keep as many things identical as possible. For instance, the lights that you use to grow the tomato plants have to use the same light bulbs. The trays have to be the same, just like the soil has to be the same. The amount of water has to be the same too. You should think very hard about differences that might try to sneak by you. For instance, when planting the tomato seeds, did they come from the same package? They should if you want to keep things under control. The only thing that can be different between the two identical groups is the thing that you are testing - in this case, light. The exact nature of your variables will depend on your exact science fair experiment idea.

If you changed the amount of light, AND changed the amount of water each plant received, you wouldn't know if the bigger tomatoes were because of the light, or the water! So it's absolutely important to have everything be as close to identical or "controlled" as you can get it.

Once you've done your science fair experiment, consider repeating it if you have the time! This is very impressive for science fair judges, and really helps to make your results convincing. If you conduct your experiment and the results just don't seem right, you might consider reviewing your experiment idea, and possibly even modifying your experimental design so that your science fair experiment will produce accurate results.

Design your science fair experiment to get the best results

Now it's time to think about how best to set up your science fair experiment to give you accurate and trustworthy results. You should keep in mind both the Scientific Method and the question you are trying to answer.

An experiment is made up of two nearly identical parts--let's say, two trays of tomato plants. The tiny differences that will test your hypothesis are called "variables." Let's look at the three kinds of variables.

The Independent Variable: this is a variable that you intentionally change. In the case of our tomato plant experiment, it would be the brightness of the light in Tray #1.

The Dependent Variable: this is the difference between the two parts of the experiment that happens when the independent variable is changed. In this case, it would be the size of the tomatoes in Tray #1. So you turn the up the lights in Tray #1 (the independent variable) and the tomatoes get bigger (dependent variable).

The Controlled Variables: these are the variables that are kept the same in Tray #2. In other words, when you turn the lights up in Tray #1, the lights in Tray #2 stay the same. So when the tomatoes in Tray #1 get bigger, you can say that the difference in size between the tomatoes in Tray #1 and Tray #2 is the result of the independent variable, or the light that you made brighter.

Tray #2 is called a "control group." This is an identical setup to Tray #1, but it is kept in its natural, unchanged state. Tray #1 is called the "experimental group." So when you change something in the experimental group (like the brightness of the light), the control group stays the same so that you can measure changes in you dependent variable (the size of the tomatoes).

3. The Investigation

This is what most science fairs are looking for. It is a proper scientific experiment, using the scientific method to seek out unknow answers to hypothetical questions. Basically, it's an experiment. if you want to advance to state, regional, or national science fairs, then this is probably the best type of project to choose.

More information on different types of science for proijects can be found in many books. Check your local library.

Now that you know about these three types of school science fair projects, it is important to ask your teacher about which will be acceptable for the assignment.

Once you know what type of science project you will do, you can start to determnet what the actual topic of your project will be. Let's take a look at the best way to do that.

2. The Demonstration

Like building a model, the "demonstration project" is often discouraged or even forbidden at some science fairs. It does not answer a question through experimentation, but instead illustrates a know scientific principle by demonstrating it. A tornado in a wind tunnel or an "oil drop" model of splitting the atom are examples of a "demonstration" science fair project. This type of project is discouraged because it doesn't challenge the student to think critically about scientific ides, principles or procedures.

1. A Model Kit

In this type of science project, a display of some kind is assembled in order to illustrate something related to science. A famous example is the "erupting volcano" model. This is a plaster model of a volcano that is filled with baking soda and vinegar; the reaction between the chemicals causes a violent foaming which erupts like lava. This type of science fair project requires the least amount of work, and lacks the creativity that judges look for. it is sometimes used for elementary school science fair projects, but is rarely appropriate for middle school or high school.