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Introduction to Colours and Shapes - Starter Quiz
The Story of the Statue Introduction. The Statue of Liberty is the tallest statue in the United States. It can be seen from far away. Where did such a big statue come from? A Gift from France. In 1865, a man in France wanted to help America celebrate its 100th birthday. He said France should give America a gift. The gift was the Statue of Liberty. First, the United States and France found a place to put the statue. They decided to put it on an island near New York. Building the Statue. The United States built the base for the statue. France built the statue itself. It had to look good and last a long time. The inside was made of iron. The outside was made of copper. The statue was put together, but it was too big to move in one piece. So it was taken apart again! The pieces were sent to America on a big ship. The statue was finally done in 1886. The president of the United States spoke at a big celebration. Big and Green. The Statue of Liberty now looks like a big green woman. It weighs as much as 115 cars. It is as tall as a 30-story building with the base. The statue started out the color of a new penny. Over the years, the air turned the copper green. What the Statue Means. The Statue of Liberty is a work of art. It is also a sign of friendship. It has welcomed many people who have moved to the United States. The Statue of Liberty also has special meaning. The torch in its right hand stands for freedom. The tablet in its left hand has July 4, 1776, written on it. The United States became its own country on this date. Visiting the Statue. Many people from around the world visit the Statue of Liberty each year. They come to see the statue that stands for freedom.
All About Kites Introduction. A kite is one of the oldest toys. And it's very simple to make. Kites come in many sizes, shapes, and colors. Did you know that kites can be both toys and tools? History of Kites. Kites were named after the kite bird. The kite bird has wide wings and easily floats high in the sky. No one knows who made the first kite. But one famous Chinese story about a kite was written over 2,000 years ago. The story is about a man who used a kite to attack a fort. He couldn't find a way to get inside the fort. So he tied himself to a huge kite. He flew over the wall of the fort and scared the soldiers! The inventor Ben Franklin had the idea that lightning was made of electricity. He wanted to prove his idea. One day when it was stormy, he tied a metal key to a kite string. Then he flew the kite up into the storm clouds. Lightning from the storm hit his kite. The electricity ran down the wet string to the metal key. When he reached for the key, he got a surprise. The electricity jumped from the key and gave him a shock! Do not try this yourself. It's not safe to do. When Ben Franklin tried to do it again, he was hurt badly. Many Uses for Kites. Some people have used kites for fishing. They put a fishhook and bait on the long kite tail. The kite tail dragged in the water. When a fish saw it, it bit the bait and was caught on the hook. Then the kite was pulled in. Weather kites carried scientific gauges into the sky. The gauges measured how fast the wind was blowing and how cool the air was. Years ago, some armies used kites with cameras to spy on enemy troops. Kites were also used as flying targets. The kites trained soldiers to aim better. Soldiers shot at the kites. The moving kites were hard to hit with bullets. Different shapes of kites fly in different ways. Flat, diamond-shaped kites fly easily. Box-shaped kites can hang still in the air for a long time. Stunt kites twist and twirl on many strings. Large parafoil kites act almost like parachutes. Giant dragon kites flutter. Fighting kites can be used to cut other kites' strings. On a breezy day, take your kite to a flat, open area. Be sure that there are no power lines or big trees. Look at the ground around you. Is there anything you could trip over? Hold your kite up by the bridle and run into the wind. Let go of the kite and slowly let out some string. Then let out a little more until your kite is high in the sky. Happy flying!
Rainbows Introduction. When the Sun comes out after it rains, run outside. You may see a rainbow in the sky. Rainbows are tricks made by light. We can see them, but we can't touch them or walk around them. They seem to move away when we try to get close to them. Science can explain how rainbows happen. Where and When Rainbows Appear. Look around the next time you see a rainbow. The Sun will be shining from behind you. There will be rain in front of you, where you'll see the rainbow. Rainbows need water drops and sunlight to form. They can even form under a bright moon. These are called moonbows. We usually see a rainbow as a half circle. It actually forms a full circle. From the ground, we can only see the top half. How Rainbows Form. Years ago, a French scientist studied rainbows. He found that to see a rainbow, you must be in the right spot. Knowing how light moves helps explain rainbows. Think of running on land. Now think of trying to run through water. You will move more slowly through water because it is thicker than air. This pencil seems to bend where it enters the water. In the same way, light moves faster through air than through water. As the light moves through water, it slows down and bend. Rainbows form when water drops meet sunlight. The light bends when it goes into each drop. Then it reflects, or bounces, off the back of each drop. The light bends again as it leaves the drop. This happens in millions of water drops at once, making the colors of a rainbow. The Colors of the Rainbow. Sunlight is made up of many colors. Water drops split the sunlight into different colors. Splitting light makes a rainbow. You have to be in the right spot to see a rainbow. Each water drop reflects colored light at a slightly different angle. The colors of the rainbow always appear in the same order. The name ROY G. BIV can help you remember the seven main colors. They are red, orange, yellow, green, blue, indigo, and violet. Conclusion. Rain stops and the Sun comes out. A beautiful rainbow sweeps across the sky. Most people find it hard not to stop and stare when a rainbow appears. Science explains how rainbows form. Still, a rainbow is always a magical sight to see.
What Pet Should You Get? Introduction. Almost every kid has wanted to have a pet. Pets can make good friends. But how do you decide which kind of pet to get? Here are some kids who have some opinions about pets. Read what they have to say. Then decide what kind of pet you would like to have. Dogs as Pets. Every kid should own a dog. A dog comes when you call it. You know it likes you because it wags its tail. Dogs like to play chase with you. Some dogs will even play catch! Get a dog for a great playmate! Dogs as Pets. Dogs are hard pets to keep. They need lots of space to run. What if you don't have a yard? You have to take them on walks even if it is cold. The worst thing is that you have to clean up after them. Yuck, who wants a dog? Lizards as Pets. Lizards make the coolest pets. They don't bark or meow. You don't have to take them for walks. They are easy to hold and to pet. It doesn't cost much for lizard food. So, go get a lizard! Lizards as Pets. It is mean to keep lizards as pets. Some have to stay in one tiny box their whole life. Some of them eat live crickets. Plus, it feels really weird to pet them. Never, ever, get a lizard! Fish as Pets. Fish make awesome pets. They come in such pretty colors. It is fun to watch them swim back and forth. It is fun to watch their funny mouths. They only need to be fed once a day. Fish make fun and easy pets to keep. Fish as Pets. Fish should be left in the oceans and rivers. Fish don't come when you call them. They can't do any tricks. And worse than that, fish don't like to be touched. Fish win the most boring pet award. Parrots as Pets One of the best pets to own is a parrot. Parrots are very beautiful birds. They often do not need a cage. I love it when my parrot says "hello." Some parrots even whistle. Get a parrot and teach it to talk. Parrots as Pets Parrots are really messy pets. They spill seeds and fruit all over. They are not the best drinkers. They get water on the floor. Their feathers can even fall out. Don't get a parrot unless you like cleaning! Conclusion. There are good things and bad things about each pet. You have to decide whether the good things are great. You have to decide whether the bad things are okay for you. You also have to do research to see whether your house is good for a pet. Don't get a pet unless you have thought hard about it. But the right pet can be your best friend!
The Philippine Flag Our country is officially identified through our flag. The Philippine flag has three colors: white, blue, and red. White signifies purity; blue means hope and peace; and red denotes bravery. The three stars symbolize the three big groups of islands of our country-the Luzon, Visayas, and Mindanao. The eight rays of the sun signify the eight provinces that first revolted against the Spaniards. These are Bulacan, Pampanga, Tarlac, Nueva Ecija, Laguna, Batangas, Manila, and Cavite. We respect our flag to show that we respect our country. We should not treat it like an ordinary cloth because it symbolizes our country. An old flag should be burned and not be used as a rag. Title: National Hero Body text: Dr. Jose Rizal was from a middle-class family from Calamba, Laguna. He is regarded as a genius who fought the Spaniards through his writings, especially the novels "Noli Me Tangere" and "El Filibusterismo." The two novels exposed the anomalies and wrongdoings of the Spanish government against the Filipino people. He wrote the poem "Mi Ultimo Adios" the eve before his execution in Bagumbayan (now known as Rizal Park). National Fruit A mango is sour when it is green, but very sweet when it is ripe. This heart-shaped fruit symbolizes the kindness of the Filipinos. It has a big tree that bears fruits abundantly during summer. National Animal A carabao is a model of hard work and industry. It is the best companion of farmers in the field. It is black and looks like a tamaraw. A carabao is a very strong animal in terms of work. It symbolizes the Filipinos as hardworking and patient. National Bird The Philippine eagle, also known as haribon, stands over 5 feet (1.6 m) tall. It has a large, sharp, and aggressive beak and has powerful talons. Philippine eagles are excellent hunters, and live in tropical rainforests. These eagles lay just one or two eggs each year. National Tree The narra is a hardy tree that grows big and is found mainly in the Bicol Region, Mindanao, and Cagayan Valley forests. Most of the desks and tables in schools are made of narra. It signifies the strong personality of Filipinos in facing trials in life. National Flower The sampaguita has white, star-shaped petals with a sweet fragrance. It is made into garlands, which are given to visitors and special persons on occasions. It signifies purity and among Filipino women. National Fish Bangus or milkfish is our national fish. It grows in ponds or freshwater and tastes delicious. Its white, shiny scales signify our beautiful country. National Dance Cariñosa is a dance of love using a handkerchief and a fan. It symbolizes the true love expressed by Filipinos. National House A nipa hut is a small but beautiful house made from bamboo and sawali or cogon leaves. Filipinos used this kind of house during the olden times. At present, there are still people using this as a dwelling place, but most of the time, they use it as a rest place or cottage. National Costume Barong Tagalog is the national costume for Filipino men. It is made from pineapple fiber or other native materials. Filipinos wear this on special occasions such as formal events or weddings. Baro at Saya is the national dress for Filipino women. Most of them are made from jusi or pineapple fiber and other native materials. This dress shows the gracefulness of Filipino women. National Leaf Our national leaf is a palm tree. It is wide and narrow like an open fan. Farmers use this to protect their crops from the harsh sunlight and rain. It grows like a tree with thorns in its body. National Language Our national language is Filipino, which is based in Tagalog. Through the efforts of former President Manuel L. Quezon (known as the "Father of the National Language"), Filipino was widely disseminated and is now used in all parts of the country. With this, Filipinos in different cultures and native tongues can still communicate with each other. National Food Lechon (litson) is an important dish served at many occasions, especially on fiestas. Lechon is a suckling pig, slowly roasted over live coals to make it crispy and tasty. National Footwear Bakya is the national footwear of the Philippines. It was most popular from the 1950s to the 1970s before the introduction of rubber slippers. There are several colors and designs of bakya that suit the taste of most Filipinos. Valuing Our National Symbols Symbols represent a country and its people. We have to respect and value these symbols because they tell something about our country and of who we are as Filipinos. Here are some ways of valuing our national symbols: When singing the national anthem, stand straight and place your right hand on your left chest. Remove your cap or close your umbrella. Ask the people walking to stop while the flag is being raised. Tell other children to stop chatting while singing the national anthem. Most importantly, sing the national anthem wholeheartedly. Retirement of a Flag: A worn-out flag should be disposed of respectfully. It should be burned in a dignified ceremony, not thrown away or used for other purposes. Help in saving and conserving our forests. They serve as habitat of our national bird and other animals. You may also help organizations that promote reforestation, clean and green programs, and tree planting activities. Do not pick flowers when visiting parks. Instead, help in keeping these places clean and beautiful. Avoid throwing thrash in their surroundings. Patronize products that are made here in our country and made by Filipinos. Tell your family and friends to buy products of the Philippines especially those of which are our national symbol. Aside from patronizing our own products, let us use and love our national language. It is good to learn foreign languages, but do not forget to use our own language correctly and proudly.
Make mcq quiz with 4 option in which one is correct -'10 Basis of Material Science • .....;;;";;;"~~;;,,;;,,,,;.;.,,;;,,,;,,;.;,.,------------ 6. Temporary materials: Some materials are meant to be placed in the oral cavity for a short period of time for different reasons. • Temporary crowns: While a permanent crown is prepared in the dental laboratory, the patient must wait for few days before it can be fabricated and cemented into place. Does patient experience any problems during this time period? If the tooth is vital (the pulp is alive), the patient is likely to experience pain and sensitivity while eating and drinking, also it looks unesthetic. What can be done to solve this problem? A temporary crown is placed before the patient leaves the clinic. It is constructed and luted in the same appointment in which the crown preparation is done. Temporary crowns are not very strong or esthetic but they serve adequately till the permanent crown is ready to be cemented. • Temporary restorations: Sometimes it is difficult to decide immediately the best line of treatment for a particular tooth. The exact condition of the pulp may not be obvious to the dentist from the patient's symptoms. A dentist removes all or part of the decay and then places a temporary restoration to have time to observe the behaviour of the pulp or to give the pilip time to heal before deciding the further treatment required. Classification based on Location of Fabrication 4,9 Materials can be classified based on the location of fabrication into: • Direct restorative materials. • Indirect restorative materials Direct restorative materials: They include those materials which are used to restore cavity preparations directly in the oral cavity (Box 1.5). Box 1.5: Examples of direct restorative materials Amalgam, composites, glass ionomer and other materials, which set by chemical reactions in the mouth. Indirect restorative materials: It includes those restorations which must be fabricated outside the mouth, indirectly on a cast/ model/ die, because their processing condition would harm oral tissues. Materials used in the construction of such prosthesis are called indirect restorative materials (Box 1.6). Box 1.6: Examples of indirect restorative materials Gold inlays, crowns of metal, ceramic and polymers, which are processed at elevated temperatures. Some indirect composite restorations can be processed under specific wavelength of light, e.g. Ceramage. Classification based on Longevity of Use 1. Permanent restorations: These restorations are not planned to be replaced for a particular time period. Though they are referred to as permanent, actually they are not, e.g. fillings, crowns, bridges and dentures do not last forever (Fig. 1.5). 2. Temporary restorations: These restorations are planned to be replaced in a short period of time, such as few days to weeks. For ~ Permanent C/) c c -.2 0 c- :;::; Cll co Interim ~ Q; 0 .8ll::1iJ C/) o~ Cll a:: c:=:J Temporary Time period Fig. 1.5: Diagram depicting the time period of use of a restoration. (Arrow in permanent restoration depicts that such restorations are not planned to be replaced for a long period of time.) Introducton to Dental Materials Dental materials Box 1.7: Characteristics of metals 1. High thermal and electrical conductivity 2. Ductility (pure metals are very soft and they can be bent without breaking) 3. Opacity (they do not transmit light) 4. Luster (they have a surface that strongly reflects light and appears bright and shiny) 5. They tend to dissolve to some extent in water or other aqueous solutions, producing cations. 6. All metals are white (actually gray) except for gold, which is yellow, and copper, which is reddish. 7. All metals are solid at room temperature except mercury, which is liquid at room temperature and is used with silver alloys as amalgam. 8. All metals have high melting temperatures because of high strength of the metallic bond that holds the atoms together. 3. Polymers 4. Composites Composites are mixtures of two or more of the first three classes in which the different components remain distinct from one another in the final structure. A common example is composite resin. Fig. 1.7a: Three-dimensional structure of iron (metal) Metals Metals are the oldest of the three classes of materials that have been used as dental materials. Metals are characterized by metallic bonds (Box 1.7) which will be discussed in the next chapter. Metals solidify with their atoms in a regular or crystalline arrangement (see Chapter 2), often in the form of a cube (Fig. 1.7a). example, temporary fillings done in a tooth during root canal treatment, which have to be replaced within 2-4 days during subsequent visits. They are used to protect the tooth and provide function till the final restoration is done. 3. Interim restoration: At times, dental treatment requires "long-term" definite temporary restorations or "interim" restorations. For examle, a 7-year-old child, met with trauma and fractured one of his central incisors. A large composite build- up may serve his immediate requirement until the root formation is completed and a permanent crown is placed. 5 Classification based on the Chemical Nature of the Material These are the atoms that make up a material and the way they are bonded together determine the properties of that materiaLS Weak bonds make for weak materials and vice versa (Table 1.4). Materials can be classified into different categories based on their primary atomic bonds (Fig. 1.6): 1. Metals 2. Ceramics Fig. 1.6: Classification of dental materials based on chemical nature 12 Basis of Material Science Box 1.9: Benefits of ceramics in dentistry 1. Many ceramic oxides are used as pigmenting agents. These oxides produce good range of colors. Due to this characteristic, we are able to match almost any tooth color with good esthetic results. 2. They are inert, i.e. not chemically reactive. This quality provides ceramics with good bio- compatibility. 3. Ceramic materials are translucent, like natural teeth. This translucency gives the ceramic crown a more natural appearance than any other dental material. Fig. 1.7b: Internal arrangement of tetrahedral structure of ceramic (silica) four large oxygen atoms surround smaller silicon atom Ceramics A ceramic is a compound formed by the union of a metallic and a non-metallic element (Box 1.8). Most of these materials are oxides, formed by the union of oxygen with metals such as silicon, aluminum, calcium and magnesium (Fig.1.7b). Ceramics may be simple or complex. Examples of simple ceramics are alumina and silica. Examples of complex ceramics are feldspar (potassium aluminum silicate) and kaolin (hydrated aluminum silicate). Ceramics may be crystalline or non- crystalline (i.e. amorphous). Porcelain is a specific type of ceramic used extensively in dentistry (Box 1.9). Box 1.8: Characteristics of ceramics 1. High melting points. 2. Brittleness, which means they cannot be bent or deformed (no sliding) to any extent without actually cracking and breaking. 3. They are poor conductor of heat and electricity. 4. They are chemically inert. 5. They have excellent esthetic result in terms of matching natural teeth. Fig. 1.8: Stucture of synthetic polymer Polymers They are the latest addition (early to mid- 1900s) to dental materials. Most of the polymers are nowadays synthesized by humans. Polymers are giant, long-chain organic molecules (Fig. 1.8). Polymers are characterized by covalent bonds within each molecule, giving them tremendous strength in a single direction. Try to break a nylon rope by pulling it! They are poor conductors of heat and electri- city. Most polymers have a structure containing thousands of carbon atoms linked together like beads on a string. Others, such as silicone polymers are formed with silicon-oxygen bonds. Introducton to Dental Materials Table 1.4: Characteristics of different materials 13 Characteristics Bond Properties Crystal structure Metals Metallic bonding High strength and hardness, high electrical and thermal conductivity BCC, FCC, or HCP unit cells Ceramics Ionic or covalent bonding, or both High hardness and stiffness, electrically insulating, refractory, and chemically inert Crystalline or amorphous Polymers Covalent bonding Low sensitivity, high electrical resistivity, and low thermal conductivity, strength and stiffness vary widely Amorphous and crystalline Composites Composites are combinations of any of the basic ceramic, metallic and polymeric materials (Box 1.10). Each material that makes up composites is called a phase. Their properties tend to be somewhere between those of their basic constituents and are used to enhance their performance, longevity and handling chracterstics. Box 1.10: Types of composites in dentistry 1. Ceramic - metallic composite: Tungsten carbide bur. 2. Metal - polymer composite: Die materials in dental laboratory. 3. Ceramic - polymer composite: Enamel, dentin, bone and restorative composites. A composite is a kind of "combination" of materials, which compliment each other. The properties lacking in one material are compensated by those of the other material. For example, restorative composite has two phases, namely resin and fillers. Teeth and bones are examples of natural composites. Enamel is a composite of hydroxyapatite (which is a ceramic material) and protein (which is a polymer). EVALUATION OF DENTAL MATERIALS Most manufacturers of dental materials maintain a quality assurance programme (As per international standard like ADA specifications) and materials are thoroughly tested before being released into the market for dental practitioner (Fig. 1.9). Laboratory Evaluations Most ADA/ ANSI specifications involve laboratory tests. The tests performed as per these specifications are useful but they all are performed in vitro, (carried out in the laboratory away from the clinical conditions) which have a lot of limitations in clinical practice.lO Clinical Notes 1. For example, most of the direct restorative materials are tested for their compressive strength but ultimately the material is subjected to a combination of compressive, tensile and shear stresses, which may decide the final success or failure of the material under masticatory load. 2. Similarly upper dentures mostly fracture along the midline because of bending. Hence a bending or transverse strength ~B-a-s-is-o-f-M-a-t-e-ria-I-S~c-ie-n-c-e-------------- ---------. test is far more meaningful for denture base materials than a compression test. Clinical Trials The majority of new materials are subjected to extensive clinical trials normally in co-operation with a dental college or hospital departments prior to their release. CONCLUSION As the number of available materials is going up, it is important that the dentist remains more aware about new products so that their judgement about the selection of material remains successful. Materials which have not been thoroughly evaluated should be avoided, specially with clinical dentistry falling under Consumer Protection Act (CPA). I Research and development I iI Manufacturer/analysis Ideal requirements for clinical use: Thermal, optical, mechanical, chemical, biological Available materials and their properties are evaluated Launch of new I product Choice and selection of material by the dentist Critical assessment based on clinical performance I I H feedback to I
Wonders of Nature Introduction. The world is full of interesting animals. Some animals look strange or have special skills. Let's look at some of these wonders of nature. Archerfish. Archerfish spit water at bugs. The bugs fall into the water, where the archerfish catch and eat them. Trap-Door Spider. The trap-door spider lives in a tunnel in the ground. Its home has a hidden door made of silk and dirt. The spider hides in its tunnel to hunt. Beaver. Beavers chew through tree trunks. They make dams out of trees, mud, and stones. Chameleon. Chameleons change color to hide themselves. They even change color to show how they feel. Flying Dragon. Flying dragons have skin on their sides that opens like wings. They jump and glide from tree to tree. Leaf Insect. The body parts of leaf insects look just like leaves. These animals blend in well with real leaves on trees. Leaf-Rolling Weevil. The female leaf-rolling weevil rolls a leaf into a cone. She lays her eggs inside the cone. The leaf hides and protects her eggs. Praying Mantis. The praying mantis holds its front legs in a praying position. A mantis has five eyes to help it hunt for food. Mole. Moles dig tunnels to find and eat worms. These animals have tiny eyes, but they are not blind. Sea Dragon. Sea dragons are small fish. They look like ocean plants. Their leafy parts help them catch food and hide from enemies. Conclusion. Interesting animals come in many shapes and sizes. They are all wonders of nature.