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Colors, Numbers and More in Spanish-SP. 2
Quiz by Yvonne Allford
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Alright, Isti â hereâs a longer and more detailed English version of the Isaac Newton text, still written at a level thatâs accessible for Grade 4 students, but rich enough in information to meet PISA literacy expectations and EF A2-level vocabulary. Iâve kept sentences short, clear, and with explanations for new concepts so itâs easier for young learners to follow, while still including both famous facts and lesser-known stories. âž» Isaac Newton: The Man Who Changed the Way We See the World A Boy from a Small Village Isaac Newton was born on January 4, 1643, in Woolsthorpe, a small village in England. His life was not easy. His father died before he was born. When he was just a few months old, his mother remarried and left him to live with his grandmother. Isaac missed his parents, but he kept himself busy by making things and exploring the world around him. As a child, Isaac liked to build models and machines. He made a small windmill that could turn with the wind. He built a water clock that told the time by dripping water into a container. He even made a sundial â a clock that tells the time by using the shadow of the sun. đĄ Did you know? The sundial marks that Isaac carved as a boy can still be seen today on the wall of his old house. âž» School and Curiosity When Newton first went to school, he was not the top student. At first, he did not pay much attention in class. But one day, another boy teased him for not being smart. Newton decided to study hard to prove him wrong. Soon, he became the best in his class. Isaac loved asking questions. He wanted to know how and why things happened. He enjoyed watching the stars at night and thinking about how the world worked. âž» The Falling Apple and Gravity One of the most famous stories about Newton is the falling apple. One afternoon, Isaac sat in his motherâs garden and saw an apple drop from a tree. This made him think: âWhy does the apple fall straight down? Why doesnât it fly up into the sky?â From this question, Newton began to think about gravity â an invisible force that pulls objects toward each other. Gravity is what keeps our feet on the ground. Itâs also what keeps the Moon moving around the Earth and the planets moving around the Sun. đĄ Fun fact: The apple did not hit Newtonâs head. Thatâs just a story people made up later to make the tale more exciting. âž» Newtonâs Three Laws of Motion Newton studied movement and wrote three important rules: 1. Objects stay still or keep moving unless something makes them change. âą Example: A ball will not roll unless you push it. 2. The bigger the push, the bigger the movement. âą Example: If you kick a ball harder, it will go faster and farther. 3. Every action has an equal and opposite reaction. âą Example: When you jump off a boat, the boat moves backward as you move forward. These three laws are still used today to understand how cars, rockets, and even roller coasters work. âž» Discoveries in Light and Color Newton also studied light. He found that white light is not just one color â it is made of many colors. He used a glass prism to split sunlight into a rainbow. This helped scientists understand how colors work. âž» Inventions and New Ideas Newton made a special telescope that used mirrors instead of lenses. This type of telescope made images of planets and stars much clearer. It is still called the Newtonian telescope today. He also worked in mathematics and helped create a new type of math called calculus, which is used to study changes and movement. âž» Strange Experiments Newton was so curious that he sometimes tested ideas on himself. Once, he put a thin needle, called a bodkin, beside his eye to see how it would change his vision. It was very dangerous, but luckily he did not go blind. đĄ Did you know? Newton also studied alchemy â an old kind of science where people tried to turn metal into gold. He never succeeded, but it showed how wide his interests were. âž» Later Life and Work At the age of 27, Newton became a professor at Cambridge University. He later worked for the Royal Mint, making sure coins were made safely and stopping people from making fake money. He was very strict, and some criminals were sent to prison because of his work. Newton never married. He spent most of his life reading, writing, and doing experiments. âž» The End of His Life Isaac Newton died in 1727 at the age of 84. He was buried in Westminster Abbey, a famous place in London where great people of Britain are honored. His work changed the world forever. Even today, scientists, engineers, and students still use Newtonâs laws and ideas. đŹ Newton once said: âIf I have seen further, it is by standing on the shoulders of giants.â This means we can make new discoveries by learning from the work of others who came before us. give 10 questions to each passage with PISA literacy standard for kid 10 years, 1. Nikola Tesla: The Man Who Dreamed of Lightning Born: July 10, 1856 Died: January 7, 1943 When Nikola Tesla was a boy in Croatia, he saw a flash of lightning and asked his mother, âCan we catch the light?â That question never left him. As he grew older, Tesla became a brilliant inventor, especially fascinated by electricity. He believed in a future where energy could be sent wirelessly through the airâlike music through the radio! Tesla invented the alternating current (AC) system, which became the foundation of modern electricity. At the time, Thomas Edison promoted direct current (DC), and the two men had a fierce competition. Many laughed at Tesla's bold ideas, but he never gave up. He dreamed of wireless communication, flying machines, and even free energy for everyone. Though he died alone and poor, today the world honors his vision. Think About It: Why do you think people didnât believe Tesla at first? What can we learn from Teslaâs courage to dream big? 2. Charles Darwin: The Man Who Studied the Worldâs Weirdest Creatures Born: February 12, 1809 Died: April 19, 1882 When young Charles Darwin got on a ship called HMS Beagle, he didnât know he would change science forever. He sailed around the world for five years, collecting plants, animals, and fossils. On the GalĂĄpagos Islands, he noticed something curious: finches had different beaks depending on their island. Why? Darwinâs observations led him to write the theory of evolution by natural selection. It explained how animals adapt and survive. But his ideas shocked many people because they seemed to challenge religious beliefs. Despite the controversy, Darwin continued his work. His book On the Origin of Species changed how we see life on Earth. Think About It: Should scientists share their ideas even if they go against what others believe? How did traveling help Darwin make new discoveries? 3. Marie Curie: The Woman Who Glowed in the Dark Born: November 7, 1867 Died: July 4, 1934 Marie Curie was born in Poland at a time when girls were not allowed to study science. But that didnât stop her. She moved to France, worked day and night, and discovered radioactivity, a powerful energy hidden inside atoms. She and her husband, Pierre Curie, found two new elements: polonium and radium. She became the first woman to win a Nobel Prize, and the only person to win in two different sciences: physics and chemistry. Even when Pierre died in an accident, Marie continued their work. Her discoveries helped doctors treat cancerâbut working with radioactive materials also harmed her health. She died from radiation exposure, but her legacy lives on. Think About It: What challenges did Marie Curie face as a woman in science? Why is it important to balance discovery with safety? 4. Galileo Galilei: The Star Watcher Who Defied the Church Born: February 15, 1564 Died: January 8, 1642 Galileo loved looking at the stars. He built one of the first powerful telescopes and made stunning discoveries: mountains on the Moon, moons around Jupiter, and that the Earth orbits the Sunânot the other way around. This idea, called heliocentrism, went against the teachings of the Church. He was put on trial and forced to say he was wrong. But he wasnât. He spent his last years under house arrest, quietly writing. Today, Galileo is called the father of modern science for daring to question what others blindly believed. Think About It: Why do you think Galileo was punished for telling the truth? Should science always follow evidence, even if it goes against powerful beliefs? 5. Isaac Newton: The Man Who Asked âWhy?â When an Apple Fell Born: January 4, 1643 Died: March 31, 1727 One day, an apple fell from a tree, and Isaac Newton began to wonder: Why did it fall down, not sideways or up? This simple question led to his theory of gravity. Newton also invented calculus, described the laws of motion, and changed physics forever. But Newton wasnât just a geniusâhe was curious, quiet, and often worked alone. He believed everything in nature followed rules, and it was our job to discover them. Thanks to him, we understand how planets move, how rockets launch, and why you fall when you trip. Think About It: How did Newtonâs curiosity lead to great discoveries? Do you think working alone helped or hurt Newton? 6. Ada Lovelace: The First Computer Programmer Before Computers Existed Born: December 10, 1815 Died: November 27, 1852 Ada Lovelace was the daughter of the famous poet Lord Byron, but she didnât love poetryâshe loved numbers! At a time when girls were expected to sew, Ada studied mathematics. She met Charles Babbage, who designed an early computer called the Analytical Engine. Ada imagined the machine could do more than just mathâit could create music, art, and even write! She wrote what is now considered the first computer program, long before real computers were built. Think About It: How did Ada imagine something that didnât exist yet? Why do we call her a pioneer in technology? 7. Albert Einstein: The Man Who Brought Time and Space Together Born: March 14, 1879 Died: April 18, 1955 Albert Einstein wasnât always a good student. In fact, his teachers thought he was slow. But Einstein thought deeply. He asked big questions like, âWhat if you could ride a beam of light?â His theories of relativity changed how we see space, time, and gravity. He also warned the world about the dangers of nuclear weapons, even though his ideas helped create them. Einstein believed science should help people, not harm them. With his messy hair, kind smile, and brilliant mind, he remains a symbol of genius. Think About It: Can someone be bad in school but still be brilliant? Should scientists be responsible for how their inventions are used? 8. Pythagoras: The Musician Who Loved Math Born: Around 570 BC Died: Around 495 BC Long ago in ancient Greece, Pythagoras believed the universe followed numbers. He discovered the Pythagorean Theorem, a rule about triangles that helps us build houses, design computers, and navigate space. He also believed that music had math inside itâthat certain notes made perfect harmony because of mathematical ratios. Pythagoras started a secret school and taught his students to search for truth through numbers, shapes, and sound. Think About It: Why do you think Pythagoras saw math in everything? How does music relate to math? 9. Rosalind Franklin: The Woman Behind the DNA Discovery Born: July 25, 1920 Died: April 16, 1958 Rosalind Franklin loved looking closely at things. She used a special machine called X-ray crystallography to photograph molecules. One of her greatest photos, called Photo 51, showed the shape of DNA, the molecule that carries lifeâs instructions. But her work was taken without credit. Two men, Watson and Crick, used her photo to build their famous model of DNA and won the Nobel Prize. Rosalind died young and never knew how important her work became. Think About It: Why is it important to give credit in science? What can we learn from Rosalindâs quiet strength? 10. Carl Linnaeus: The Man Who Gave Names to Everything Born: May 23, 1707 Died: January 10, 1778 Have you ever wondered why a tiger is called Panthera tigris? Thatâs thanks to Carl Linnaeus, a Swedish scientist who created a way to name and organize every living thing. His system is still used today in biology. Linnaeus loved nature and spent his life collecting plants, animals, and even rocks. He believed that by organizing life, we could better understand it. Thanks to him, we now have a global âdictionary of nature.â Think About It: Why is it important to name and organize living things? How does order help us understand the world?
A BAD CASE OF THE STRIPES By David Shannon Parts(18): Camilla Narrator 1 Narrator 2 Narrator 3 Narrator 4 Mr. Harms Mother Father Dr. Bumble Old Woman Environmental Therapist Dr. Grop Dr. Gourd Dr. Sponge Mr. Mellon Dr. Cricket Dr. Young <><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><> Narrator 1: A BAD CASE OF THE STRIPES By David Shannon Narrator 2: Camilla Cream loved lima beans. But she never ate them. Narrator 3: All of her friends hated lima beans, and she wanted to fit in. Camilla always worried about what other people thought of her. Narrator 4: Today she was fretting even more than usual. It was the very first day of school, and she couldn't decide what to wear. There were so many people to impress! Narrator 1: She tried on forty-two outfits, but none seemed quite right. She put on a pretty red dress and looked in the mirror. Then she screamed. Narrator 2: Her mother ran into the room, and she screamed, too. Mother: "Oh my heavens! You're completely covered with stripes!" Narrator 3: she cried. This was certainly true. Camilla was striped from head to toe. She looked like a rainbow. Narrator 4: Mrs. Cream felt Camilla's forehead. Mother: "Do you feel all right?" Narrator 1: she asked. Camilla: "I feel fine, but just look at me!" Narrator 2: Camilla answered. Mother: "You get back in bed this instant. You're not going to school today." Narrator 3: her mother ordered. Camilla was relieved. She didn't want to miss the first day of school, but she was afraid of what the other kids would say. And she had no idea what to wear with those crazy stripes. Narrator 4: That afternoon, Dr. Bumble came to examine Camilla. Dr. Bumble: "Most extraordinary! I've never seen anything like it! Are you having any coughing, sneezing, runny nose, aches, pains, chills, hot flashes, dizziness, drowsiness, shortness of breath, or uncontrollable twitching?" Narrator 1: he asked. Camilla: "No, I feel fine." Narrator 2: Camilla told him. Dr. Bumble: "Well then, I don't see any reason why she shouldn't go to school tomorrow. Here's some ointment that should help clear up those stripes in a few days. If it doesn't, you know where to reach me." Narrator 3: Dr. Bumble said, turning to Mrs. Cream. And off he went. Narrator 4: The next day was a disaster. Everyone at school laughed at Camilla. They called her "Camilla Crayon" and "Night of the Living Lollipop." Narrator 1: She tried her best to act as if everything were normal, but when the class said the Pledge of Allegiance, her stripes turned red, white, and blue, and she broke out in stars! Narrator 2: The other kids thought this was great. One yelled out, Narrator 3: "Let's see some purple polka dots!" Narrator 4: Sure enough, Camilla turned all purple polka-dotty. Someone else shouted, Narrator 1: "Checkerboard!" Narrator 4: and a pattern of squares covered her skin. Soon everyone was calling out different shapes and colors, and poor Camilla was changing faster than you can change channels on a T.V. Narrator 2: That night, Mr. Harms, the school principal, called. Mr. Harms: "I'm sorry, Mrs. Cream, I'm going to have to ask you to keep Camilla home from school. She's just too much of a distraction, and I've been getting phone calls from the other parents. They're afraid those stripes may be contagious." Narrator 3: he said. Camilla was so embarrassed. She couldn't believe that two days ago everyone liked her. Now, nobody wanted to be in the same room with her. Narrator 1: Her father tried to make her feel better. Father: "Is there anything I can get you, sweetheart?" Narrator 2: he asked. Camilla: "No, thank you," Narrator 3: sighed Camilla. What she really wanted was a nice plate of lima beans, but she had been laughed at enough for one day. Dr. Bumble: "Hmm, well, yes, I see. I think I'd better bring in the Specialists. We'll be right over.â Narrator 4: said Dr. Bumble to Mr. Cream on the phone. About an hour later, Dr. Bumble arrived with four people in long white coats. He introduced them to the Creams. Dr. Bumble: "This is Dr. Grop, Dr. Sponge, Dr. Cricket, and Dr. Young." Narrator 1: Then the Specialists went to work on Camilla. They squeezed and jabbed, tapped and tested. It was very uncomfortable. Dr. Grop: "Well, it's not the mumps." Dr. Sponge: "Or the measles." Dr. Cricket:"Definitely not chicken pox." Dr. Young: "Or sunburn." Narrator 2: replied the Specialists. Specialists:"Try these. Take one of each before bed." Narrator 4: said the specialists. They each handed her a bottle filled with different colored pills. Then they filed out the front door followed by Dr. Bumble. Narrator 1: That night, Camilla took her medicine. It was awful. Narrator 2: When she woke up the next morning, she did feel different, but when she got dressed, her clothes didn't fit right. She looked in the mirror, and there, staring back at her, was a giant, multi-colored pill with a face on it. Narrator 3: Dr. Bumble rushed over as soon as Mrs. Cream called. But this time, instead of the Specialists, he brought the Experts. Narrator 4: Dr. Gourd and Mr. Mellon were the finest scientific minds in the land. Once again, Camilla was poked and prodded, looked at and listened to. Narrator 1: The Experts wrote down lots of numbers. Then they huddled together and whispered. Dr. Gourd finally spoke. Dr. Gourd: "It might be a virus," Narrator 2: he announced with authority. Suddenly, fuzzy little virus balls appeared all over Camilla. Mr. Mellon: "Or possibly some form of bacteria," Narrator 3: said Mr. Mellon. Out popped squiggly little bacteria tails. Dr. Gourd: "Or it could be a fungus," Narrator 4: added Dr. Gourd. Instantly, Camilla was covered with different colored fungus blotches. The experts looked at Camilla, then each other. Experts: "We need to go over these numbers again back at the lab. Weâll call you when we know something," Narrator 1: said the Experts. But the Experts didn't have a clue, much less a cure. Narrator 2: By now, the T.V. news had found out about Camilla. Reporters from every channel were outside her house, telling the story of "The Bizarre Case of the Incredible Changing Kid." Narrator 3: Soon a huge crowd was camped out on the front lawn. Narrator 4: The Creams were swamped with all kinds of remedies from psychologists, allergists, herbalists, nutritionists, psychics, an old medicine man, a guru, and even a veterinarian. Narrator 1: Each so-called cure only added to poor Camilla's strange appearance until it was hard to even recognize her. She sprouted roots and berries and crystals and feathers and a long furry tail. But nothing worked. Narrator 2: One day, a woman who called herself an Environmental Therapist claimed she could cure Camilla. She said, Environmental Therapist: "Close your eyes, breathe deeply, and become one with your room." Camilla: "I wish you hadn't said that," Narrator 3: Camilla groaned. Slowly, she started to melt into the walls of her room. Her bed became her mouth, her nose was a dresser, and two paintings were her eyes. The therapist screamed and ran from the house. Mother: "What are we going to do? It just keeps getting worse and worse!" Narrator 4: cried Mrs. Cream. She began to sob. Narrator 1: At that moment, Mr. Cream heard a quiet little knock at the front door. He opened it, and there stood an old woman who was just as plump and sweet as a strawberry. Old Woman: "Excuse me, but I think I can help." Narrator 2: she said brightly. Narrator 3: She went into Camilla's room and looked around. Old Woman: "My goodness, what we have here is a bad case of the stripes. One of the worst I've ever seen!" Narrator 4: she said with a shake of her head. She pulled a container of small green beans from her bag. She said, Old Woman: "Here. These might do the trick." Mother: "Are those magic beans?" Narrator 1: asked Mrs. Cream. The old woman replied, Old Woman: "Oh my, no, there's no such thing. These are just plain old lima beans. I'll bet you'd like some, wouldn't you?" Narrator 2: she asked Camilla. Camilla wanted a big, heaping plateful of lima beans more than just about anything, but she was still afraid to admit it. She said, Camilla: "Yuck! No one likes lima beans, especially me!" Old Woman: "Oh, dear, I guess I was wrong about you." Narrator 3: said the old woman sadly. She put the beans back in her bag and started toward the door. Narrator 4: Camilla watched the old woman walk away. Those beans would taste so good. And being laughed at for eating them was nothing, compared to what she'd been going through. She finally couldn't stand it. Camilla: "Wait! The truth is...I really love lima beans." Narrator 1: she cried. The old woman smiled, popping a handful of beans into Camilla's mouth, and said, Old Woman: "I thought so." Camilla: "Mmmmmmm," Narrator 2: said Camilla. Suddenly the branches, feathers, and squiggly tails began to disappear.Then the whole room swirled around. When it stopped, there stood Camilla, and everything was back to normal. Camilla: "I'm cured!" Narrator 3: she shouted. The old woman said, Old Woman: "Yes, I knew the real you was in there somewhere." Narrator 4: She patted Camilla on the head and went outside and vanished into the crowd. Narrator 1: Afterward, Camilla wasn't quite the same. Narrator 2: Some of the kids at school said she was weird, but she didn't care a bit. Narrator 3: She ate all the lima beans she wanted, and she never had even a touch of stripes again.
Align Panel: This panel allows you to align one or more objects the the artboard or other objects. Alignment: Formatting the appearance of text with the margins of the text box. Anchor Point Tool: Allows you to add or remove handles to create a curve on an anchor point. Anchor Points: A point on a path indicates a change of direction. Appearance Panel: This panel shows you the fill, strokes, graphic styles, and effects that have been applied to an object, group or layer and are able to modify theses from this panel directly. Area Type Tool: This occurs when using the type tool and you click and drag a text box, the text will automatically wrap inside the box. Blend Tool: This tool allows you to combine shapes/colors between two or more objects to create a new object between the original, blending the colors and shapes by inserting the middle steps to get from one object to the next. Blob Brush Tool: This tool is used to create free-form objects that can have a more hand-drawn feel. Brushes: Allows you to set the appearance/style of a path, can be applied to existing paths or used to create new paths. Clipping Masks: This command allows you to mask objects to a shape so that only areas that lie within the shape are visible, the mask and objects that are masked are called a clipping set. Closed Path: A path that has the same beginning and ending point. It forms a complete shape that can be filled with color or text. Create Outlines: This command converts text to closed paths and can be found in the Type Menu. Curvature Pen Tool: Allows you to simply create paths with curved anchor points. Curves: Can be applied to an anchor point using handles to create an arched line. Direct Select Tool: Allows you to select individual points of any path. Effects: These can be added to objects to create quick dynamic characteristics. Eraser Tool: This tool allows you to remove anchor points and cut through paths. Expand Objects: This allows you to divide a single object into multiple objects that make up its appearance. Eyedropper Tool: This tool allows you to sample the color or text from an existing part of the artwork. Global Swatches: This is a color swatches that will be automatically updated throughout your artwork when you change them, indicated with a white triangle in the corner of the swatch. Graphic Styles: A set of reusable appearance attributes that allow you to quickly change the look of an object. Grouping: This command allows you to link objects together so that they can be moved, scaled, rotator, or copy. Groups can be nested inside other groups. Hierarchy: To create visual order in design, controlling what the viewer looks at in order using size, color, contrast, etc⊠Image Trace: This command allows you to convert a raster image into a vector artwork. Isolation Mode: This mode allows you to adjust single objects/groups inside a group without ungrouping the group. Join Tool: This tool joins paths and anchor points together quickly. Kerning: This is the adjustment of the space between two individual letters. Knife Tool: This tool allows you to split an object into 2 pieces along a freehand path you draw. Leading: This is the adjustment of the space between lines of text. Live Corners: This widget appears when using the Direct Select tool and a corner is selected, when used this will create a rounded corner. Live Paint: This command allows you to quickly apply colors to objects in a complex design. Open Path: A path that does not end, not connected back to the original anchor point. Overflow Text: This occurs when the text box is too small to house all the text and is indicated by a small red plus sign in the bottom right corner of the text box. Paintbrush Tool: This tool is used to create free-form paths that can have a more hand-drawn feel. Paragraph Spacing: The space that occurs between lines of text. Pathfinder Panel: This panel allows you to create complex shapes by selecting 2 or more objects and using the buttons in the panel to cut, combine, or divide the objects. Paths: These are created when 2 or more points are connected, these are created using the pen tool. Pen Tool: It allows you to create and edit anchor points and paths. Pencil Tool: This tool is used to create free-form shapes or lines, the accuracy of the lines can be adjusted. Perspective Tool: This tool allows you to place elements on a perspective grid to adjust objects on a different perspective, automatically snapping to the perspective grid. Placeholder Text: Text that is placed in a text box that "holds a place" in a design to allow for creating a layout or adjust the text design. Point Type Tool: This occurs when when using the type tool and you click once, the text will continue without wrapping. Readability: The characteristics of fonts and styles that make test easy to identify and read. Scale, Shear, Distort Objects: This set of commands allows you to adjust the size and perspective of objects. Scissors Tool: This tool allows you to split a path into 2 pieces. Selection Tool: Allows you to select paths, objects or groups by click or dragging over them. Shape Builder Tool: This interactive tool allows you to create complex shapes by merging and erasing simpler objects. Shapes Tools: A group of tools to create basic shapes without using the pen tool (rectangle, ellipse, polygon, star, etcâŠ). Smooth Tool: This tool will smooth a complex path and reduce the number of anchor points. Swatches: This is a saved color that can be applied in a design via the swatches panel and can be grouped, these can include gradients and patterns. Text Wrapping: This is when the text in a text box automatically wraps to the next line when it reaches the edge of the box. Threading Text: This is the ability to create 2 or more text boxes that are linked, when text is added/adjusted in one box, it will affect the other(s). Touch Type Tool: This tool allows you to adjust individual letter in a previously created text box. Tracking: This is the adjustment of the overall spacing between letters. Transform Objects: This allows you to change the size of objects. Type on a Path Tool: This tool allows you to add text along any previously created path. Type Tool: This tool allows you to create text in a design. View Modes: Ability to view projects and adjust the display on the screen. Modes include Outlines, Presentation, & Full Screen.
A solution is a mixture in which one or more substances are uniformly distributed in another substance. Solutions can be mixtures of liquids, solids, or gases. For example, plasma, the liquid part of blood, is a very complex solution. It is composed of many types of ions and large molecules, as well as gases, that are dissolved in water. A solute (SAHL-YOOT) is a substance dissolved in the solvent. The particles that compose a solute may be ions, atoms, or molecules. The solvent is the substance in which the solute is dissolved. For example, when sugar, a solute, and water, a solvent, are mixed, a solution of sugar water results. Though the sugar dissolves in the water, neither the sugar molecules nor the water molecules are altered chemically. If the water is boiled away, the sugar molecules remain and are unchanged. Solutions can be composed of various proportions of a given solute in a given solvent. Thus, solutions can vary in concentra- tion. The concentration of a solution is the amount of solute dis- solved in a fixed amount of the solution. For example, a 2 percent saltwater solution contains 2 g of salt dissolved in enough water to make 100 mL of solution. The more solute dissolved, the greater is the concentration of the solution. A saturated solution is one in which no more solute can dissolve. Aqueous (AY-kwee-uhs) solutionsâsolutions in which water is the solventâare universally important to living things. Marine microorganisms spend their lives immersed in the sea, an aqueous solution. Most nutrients that plants need are in aqueous solutions in moist soil. Body cells exist in an aqueous solution of intercellu- lar fluid and are themselves filled with fluid; in fact, most chemical reactions that occur in the body occur in aqueous solutions. Copyright © by Holt, Rinehart and Winston. All rights reserved. Liquid water Solid water Ice (solid water) is less dense than liquid water because of the structure of ice crystals. The water molecules in ice are bonded to each other in a way that creates large amounts of open space between the molecules, relative to liquid water. FIGURE 2-12 solvent from the Latin solvere, meaning âto loosenâ Word Roots and Origins CHEMISTRY OF LIFE 43 ACIDS AND BASES One of the most important aspects of a living system is the degree of its acidity or alkalinity. What do we mean when we use the terms acid and base? Ionization of Water As water molecules move about, they bump into one another. Some of these collisions are strong enough to result in a chemical change: one water molecule loses a proton (a hydrogen nucleus), and the other gains this proton. This reaction really occurs in two steps. First, one molecule of water pulls apart another water molecule, or dissociates, into two ions of opposite charge: H2O â H OH The OH ion is known as the hydroxide ion. The free H ion can react with another water molecule, as shown in the equation below. H H2O â H3O The H3O ion is known as the hydronium ion. Acidity or alkalin- ity is a measure of the relative amounts of hydronium ions and hydroxide ions dissolved in a solution. If the number of hydronium ions in a solution equals the number of hydroxide ions, the solution is said to be neutral. Pure water contains equal numbers of hydro- nium ions and hydroxide ions and is therefore a neutral solution. Acids If the number of hydronium ions in a solution is greater than the number of hydroxide ions, the solution is an acid. For example, when hydrogen chloride gas, HCl, is dissolved in water, its mol- ecules dissociate to form hydrogen ions, H, and chloride ions, Cl, as is shown in the equation below. HCl â H Cl These free hydrogen ions combine with water molecules to form hydronium ions, H3O. This aqueous solution contains many more hydronium ions than it does hydroxide ions, making it an acidic solution. Acids tend to have a sour taste; how- ever, never taste a substance to test it for acidity. In concentrated forms, they are highly corrosive to some materials, as you can see in Figure 2-13. Bases If sodium hydroxide, NaOH, a solid, is dissolved in water, it dissociates to form sodium ions, Na, and hydroxide ions, OH, as shown in the equation below. NaOH â Na OH Copyright © by Holt, Rinehart and Winston. All rights reserved. Eco Connection onnection Acid Precipitation Acid precipitation, more commonly called acid rain, describes rain, snow, sleet, or fog that contains high levels of sulfuric and nitric acids. These acids form when sulfur dioxide gas, SO2, and nitrogen oxide gas, NO, react with water in the atmosphere to produce sulfuric acid, H2SO4, and nitric acid, HNO3. Acid precipitation makes soil and bodies of water, such as lakes, more acidic than normal. These high acid levels can harm plant and animal life directly. A high level of acid in a lake may kill mollusks, fish, and amphibians. Even in a lake that does not have a very elevated level of acid, acid precipitation may leach aluminum and magnesium from soils, poisoning water- dwelling species. Reducing fossil-fuel consump- tion, such as occurs in gasoline engines and coal-burning power plants, should reduce high acid levels in precipitation. Sulfur dioxide, SO2, which is produced when fossil fuels are burned, reacts with water in the atmosphere to produce acid precipitation. Acid precipitation, or acid rain, can make lakes and rivers too acidic to support life and can even corrode stone, such as the face of this statue. FIGURE 2-13 44 CHAPTER 2 This solution then contains more hydroxide ions than hydronium ions and is therefore defined as a base. The adjective alkaline refers to bases. Bases have a bitter taste; however, never taste a substance to test for alkalinity. They tend to feel slippery because the OH ions react with the oil on our skin to form a soap. In fact, commercial soap is the product of a reaction between a base and a fat. pH Scientists have developed a scale for comparing the relative con- centrations of hydronium ions and hydroxide ions in a solution. This scale is called the pH scale, and it ranges from 0 to 14, as shown in Figure 2-14. A solution with a pH of 0 is very acidic, a solution with a pH of 7 is neutral, and a solution with a pH of 14 is very basic. A solutionâs pH is measured on a logarithmic scale. That is, the change of one pH unit reflects a 10-fold change in the acidity or alkalinity. For example, urine has 10 times the H3O ions at a pH of 6 than water does at a pH of 7. Vinegar, has 1,000 times more H3O ions at a pH of 3 than urine at a pH of 6, and 10,000 times more H3O ions than water at a pH of 7. The pH of a solution can be measured with litmus paper or with some other chemical indicator that changes color at various pH levels. Buffers The control of pH is important for living systems. Enzymes can function only within a very narrow pH range. The control of pH in organisms is often accomplished with buffers. Buffers are chemi- cal substances that neutralize small amounts of either an acid or a base added to a solution. As Figure 2-14 shows, the composition of your internal environmentâin terms of acidity and alkalinityâ varies greatly. Some of your body fluids, such as stomach acid and urine, are acidic. Others, such as intestinal fluid and blood, are
Make mcq quiz with 4 option in which one is correct -'10 Basis of Material Science âą .....;;;";;;"~~;;,,;;,,,,;.;.,,;;,,,;,,;.;,.,------------ 6. Temporary materials: Some materials are meant to be placed in the oral cavity for a short period of time for different reasons. âą 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. âą 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: âą Direct restorative materials. âą 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
Science Exam Parts of the Atom: The atom consists of a nucleus at its center, containing protons (positively charged) and neutrons (neutral), while electrons (negatively charged) orbit in electron shells around the nucleus. Atomic Number: The atomic number of an element is the number of protons in its nucleus. It defines the element and determines its place on the periodic table. Properties of Metals: Metals have properties like conductivity, malleability (can be flattened into sheets), and ductility (can be drawn into wires). Elements, Compounds, and Mixtures: Elements consist of only one type of atom. Compounds are made of two or more different elements chemically bonded. Mixtures are combinations of substances that are physically mixed but not chemically bonded. Homogeneous and Heterogeneous Mixtures: Homogeneous mixtures have a uniform composition (e.g., saltwater), while heterogeneous mixtures have different phases (e.g., oil and water). Changes of State: Changes like melting, evaporation, and condensation are examples of physical changes of state. Chemical and Physical Properties: Chemical properties describe how a substance can change to form a new substance, while physical properties are characteristics like color, texture, and state (solid, liquid, gas). Physical and Chemical Change: A physical change involves the appearance or state of matter, but the substance remains the same. A chemical change involves the formation of new substances. Chemical Equations: Chemical reactions can be represented with chemical equations that show reactants (what you start with) and products (what is formed). Chemical Formulas: Chemical formulas represent the composition of compounds. For example, NaHCO3 is sodium bicarbonate, consisting of one sodium (Na), one hydrogen (H), one carbon (C), and three oxygen (O) atoms. Energy: Types of Energy: Energy can be kinetic (related to motion), potential (stored energy), thermal (heat energy), electrical, chemical, and more. Units of Energy: Common units of energy include joules (J) and calories (cal). Law of Conservation of Energy: Energy cannot be created or destroyed, only transferred or transformed from one form to another. Energy Transfer and Transformation: Energy moves from one object to another, changing forms along the way. Useful and Waste Energy: Useful energy is what can be harnessed and used for a specific purpose. Waste energy is energy that is not used and is often lost. Energy Flow Diagrams: These diagrams show how energy is transferred or transformed within a system. Energy Efficiency: Efficiency is a measure of how much useful energy is obtained from a system. It can be calculated using the equation: Efficiency = (Useful Energy Output / Total Energy Input) x 100%. Fossil Fuels and Renewable Energy: Fossil fuels, like coal, oil, and natural gas, are non-renewable sources of energy. Renewable energy sources include solar, wind, and hydroelectric power. Variables: Independent Variable: The variable that is manipulated or changed in an experiment. Dependent Variable: The variable that is measured or observed and is affected by changes in the independent variable. Controlled Variables: Factors that are kept constant to ensure a fair and accurate experiment.
Name: Marco Ramirez - âI Am Not Batmanâ TW: language Itâs the middle of the night. And the sky is glowing like mad radioactive red. And if you squint, you could maybe see the moon through a thick layer of cigarette smoke and airplane exhaust that covers the entire city like mosquito net that wonât let the angels in. And if you look up high enough you could see me-standing on the edge of a eighty seven story building. And up there-a place for gargoyles and broken clock towers that have stayed still and dead for maybe like a hundred years-up there is me. And Iâm freakin Batman. And I gots Bat-mobiles and Bat-a-rangs and freakin Bat-caves like for real, and all it takes is a broom closet or a back room or a fire escape and Dannyâs hand-me-down jeans are gone. And my navy blue polo shirt? â The one that looks kinda good on me but has a hole on it near the butt from when it got snagged on the chain linked fence behind Arturoâs but it isnât even a big deal cause I tuck that part in and its like all good? âthat blue polo shirt? â Itâs gone too. And I get like, like transformational. And nobody pulls out a belt and whips Batman for talking back â-Or for not talking back âAnd nobody calls Batman simple â- Or stupid â- Or skinny â- And nobody fires Batmanâs brother from the Eastern Taxi Company âcause they was making cutbacks, neither, âcause they got nothing but respect, and not like afraid-respect. Just like respect-respect. âCause nobodyâs afraid of you. Cause Batman doesnât mean nobody harm. Ever. Cause all Batman really wants to do is save people and maybe pay Abuelaâs bills one day and die happy and maybe get like mad famous. For real.âŠAnd kill the Joker. Tonight, like most nights, Iâm all alone. And Iâm watchingâŠAnd Iâm waiting⊠Like a eagle. Or like a âno, yea, like a eagle. And my cape is flappinâ in the wind (âcause itâs freakinâ long), and my pointy ears are on, and that mask that covers like half my face is on too, and I got like bulletproof stuff all in my chest so no one could hurt me and nobody â nobody â is gonna come between Batman, And Justice. From where I am I could hear everything. Somewhere in the city thereâs a old lady picking Styrofoam leftovers up outta a trash can and sheâs putting a piece of sesame chicken someone spit out into her own mouth. And somewhere thereâs a doctor with a whack haircut in a black lab coat trying to find a cure for the diseases that are gonna make us all extinct for real one day. And somewhere thereâs a man, a man in a janitorâs uniform, stumbling home drunk and dizzy after spending half his paycheck on forty-ounce bottles of twist-off beer and the other half on a four hour visit to some ladyâs house on a street where the lights have all been shot out by people whoâd rather do what they do, in this city, in the dark. And half a block away from JanitorMan thereâs a group of good-for-nothings who donât know no better waiting to beat JanitorMan with rusted bicycle chains and imitation Lousiville Sluggers, and if they donât find a cent on him â which they wonât â theyâll just pound at him till the muscles in their arms start burning, till thereâs no more teeth to crack out. But they donât count on me. They donât count on no dark night (with a stomach full of grocery store brand macaroni-and-cheese and cut up Vienna sausages), Cause theyâd rather believe I donât exist, And from eighty-seven stories up I could hear one of the good-for-nothings say âGimmethecashâ real fast (like that) just âGimmethefuckingcashâ and I see JAnitorMan mumble something in drunk language and turn pale and from eighty-seven stories up I could hear his stomach trying to hurl its way out of his Dickies. So I swoop down like and fast and Iâm like darkness. Iâm like SWOOSH â- And I throw a Bat-a-rang at the one naked lightbulb â- And theyâre all like âwhoa-motherfucker-who-just-turned-out-the-lights?â ââWhatâs that over there?â â-âWhat?â â- âGimme whatchou got old manâ â- âDid anybody hear that?!â â- âNo, reallyâ â- âThere ainât. No. Bat.â â But then â- One out of three good-for-nothings gets it to the head! And number Two swings blindly into the dark cape before him but before his fist hits anything I grab a trash can lid and â-- Right into the gut, and number One comes back with a jump-kick but I know judo-karate too so Iâm like â-- Twice â-- but before I can do any more damage suddenly we all hear a CLIC â CLIC âAnd suddenly everything gets quiet And the one good-for-nothing left standing grips a handgun and aims straight up, like heâs holding Jesus hostage, like heâs threatening maybe to blow a hole in the moon. And the good-for-nothing who got it to the head who tried to jump-kick me and the other good-for-nothing who got it in the gut is both scrambling back away from the dark figure before him. And the drunk man the JanitorMan is huddled in a corner, praying to Saint Anthony âcause thatâs the only one he could remember. And thereâs me, Eyes glowing white, cape blowing softly in the wind. Bulletporoof chest heaving. My heart beating right through it in a Morse code for âfuck with me, just once, come on, just try.â And the one good-for-nothing left standing, the one with the handgun, he laughs he lowers his arm, and he points it at me and gives the moon a break, and he aims it right between my pointy ears, like goalposts and heâs special teams. And JanitorMan is still calling Saint Anthony but he ainât pickinâ up, And for a second it seems likeâŠmaybe Iâm gonna lose. Naw. SHOO â SHOO! FUACATA! --âDonât kill me man!â ââSNAP! â Wrist CRACK â Neck â SLASH! â Skin â meets â acid â âAHH!!â âAnd heâs on the floor. And Iâm standing over him. And I got the gun in MY hands now. And I hate guns, I hate holding âem cause Iâm Batman, and âBatman donât like guns âcause his parents got iced by guns a long time ago â but for just a second, my eyes glow white, and I hold this thing, for I could speak to the good-for-nothing in a language he maybe understandsâŠCLIC â CLICâŠAnd the good-for-nothings become good-for-disappearing into whatever toxic-waste-chemical-sludge-shit-hole they crawled out of. And itâs just me and JanitorMan. And I pick him up. And I wipe sweat and cheap perfume off his forehead. And he begs me not to hurt him and I grab him tight by his JanitorMan shirt collar and I pull him to my face, and heâs taller than me, but the cape helps so he listens when I look him straight in the eyes and I say two words to him: âGo home.â And he does, checking behind his shoulder every ten feet. And I SWOOSH from building to building on his way there, âcause I know where he lives. And I watch his hands where he lives. And I watch his hands tremble as he pulls out his keychain and opens the door to his building. And Iâm back in bed before he even walks in through the front door. And I hear him turn on the faucet and pour himself a glass of warm tap water And he puts the glass back in the sink. And I hear his footsteps, And they get slower as they get to my room. And he creaks my door open like mad slow. And he takes a step in, which he never does. And heâs staring off into nowhere, his face the color of sidewalks in summer, and I act like Iâm just waking up, and I say, âWhatâs up, Pop?â And JanitorMan says nothing to me. But I see, in the dark, I see his arms go limp and his head turns back, like towards me, and he lifts it for I could see his face, For I could see his eyes, And his cheeks is dripping but not with sweat. And he just stands there, breathing, like he remembers my eyes glowing white. Like he remembers my bulletproof chest. Like he remembers heâs my pop. And for a long time I donât say nothing. And he turns around, hand on the doorknob, and he ainât looking up my way but I hear him mumble two words to me. âIâm sorry.â And I lean over and open my window just a crack.⊠If you look up high enough you could see me. And from where I am? I could hear everything.
Jackie Robinson Introduction. African Americans play a big part in professional sports today. For many years, however, black athletes weren't allowed to play with white athletes. Jackie Robinson helped change all that. The Early Years. Jack Roosevelt Robinson was born into a poor Georgia family in 1919. In college, he was a star on his school's football, track, basketball, and baseball teams. His family had little money, however. He left college in 1941 to help support his family and did not finish. Taking a Stand. In December 1941, the United States entered a war. Like many young men, Robinson had to serve in the war. One day, he and a group of soldiers got on an army bus. Robinson poses in his U.S. Army uniform. The bus was segregated. White soldiers sat in the front and black soldiers in the back. Yet Robinson knew he was as good a soldier as the white men. He would not move to the back when he was told to. Robinson was arrested, but he had only stood up for what was right. He was let go. You're Hired! After his time in the army, Robinson played baseball. In 1945, however, baseball was segregated, too. White and black athletes played in separate leagues. Robinson felt that there should not be separate baseball leagues based on skin color. So did Branch Rickey, the man who ran the Brooklyn Dodgers. Rickey wanted the Dodgers to be the first white team to include a black player. Rickey knew that this player would not only have to be a great athlete. He would also have to face prejudice because he was African American. Rickey hired Robinson. He had one condition, though. Robinson could only fight prejudice one way-by playing great baseball. Number 42 Takes the Field Wearing number 42, Robinson took the field on April 15, 1947. A crowd of twenty-six thousand people watched as he walked to the plate. Insults rang out from the other team's dugout, but Robinson just played ball. Equal rights won that day. So did the Dodgers. As for Robinson, he went on to have a great career. In 1962, he became the first African American to get into the Baseball Hall of Fame. Beyond Baseball. After Robinson stopped playing baseball in 1957, he went into business. He also continued to work for equal rights for all people. He died in 1972. Today in the United States, more people of color play in the world of sports than ever before. We all have Number 42 to thank for that.