5th Class

            Laws of Reflection   According to the law of reflection: Angle of incidence = Angle of reflection. Incident ray, reflected ray and normal ray all lie on the same plane.   Incident ray is the light that strikes the mirror. Angle formed between incident ray and normal to the surface is called angle of incidence. Reflected ray is the ray of light that gets reflected back after striking the surface. The angle formed between reflected ray and normal to the surface is called angle of reflection. Number of images formed between two plane mirrors when placed at an angle, where, N = Number of images formed.= Angle between the mirrors. Then, Number of images formed  if more...

       Properties of Light            Light Rays Travel in Straight Line (Rectilinear Propagation) During thunderstorm and lightening, lightening is seen before we hear thunder, because light reaches the surface first than sound. Speed of light is 3x108 m/s and the speed of sound is 340 m/s.   Look at the following pictures of luminous objects:                                                                                      Object emitting its own light                     more...

       Introduction   We all have eyes to see, but we can't see anything with these eyes in dark. It means to see objects we need light. Light is a form of energy that enables us to see. The Sun is the largest source of light. Distance between the stars is measured in light year. In this chapter, we will study about the characteristic features of light and sound.        Light A beam of white light has seven colours, which can be seen when a beam of white light is passed through a prism. When a beam of light strikes on the surface of prism, it splits into seven colours. The best example of these colour of white light is the formation of rainbow in the rain. An important property of light is that, it does more...

         Mammals   They have hair on the body. Mammals are warm blooded hence they can regulate temperatures. They have sweat glands to cool the body by taking heat from the body. Mammals give birth to young ones. They have mammary gland to feed the young ones. Mammals have four legs to walk on. They have more developed brain than other. Mammals have flippers and fins (If aquatic) instead of legs for swimming.                                                                    Bat is the smallest mammal size less than 2 cm                               more...

     Reptiles   Reptiles are cold blooded animals having dry skin covered with scales, found everywhere except in cold places. Reptiles warm themselves in the sun shine to be active. Reptiles are air breathing animals, though many live not only on land but also in water. They have tungs for breathing. Some water reptiles absorb oxygen in water through membrane in their mouth.          Alligators and Crocodiles Alligators and crocodiles are larger in size. They have webbed feet to walk on the land and long tail to swim in water- They are hunters with huge and lot of sharp teeth to tear their prey. Tails are long and powerful to swim in water. An alligator has a shorter snout than a crocodile. Alligator has a shorter snout   more...

     Birds   Animals, which live mostly in air and have feathers and wings are called as Birds. All birds have wings but not all birds can fly. Millions of year ago some birds went back to sea and their feathers are adapted according to water to help them in swimming. More than 9,000 kinds of birds are present today. The size of birds varies from the largest African ostrich (taller than and man) to the smallest humming bird of 3 - 4 cm length.   Look at the parts of body of a bird in the following picture:   General Features of Birds They have light and hollow strong bones and skull. Birds have hard beak or bill instead of teeth or mouth. They are not very big in size, except few. They have wings more...

      Fishes   Fishes are our very distant ancestors. These are believed to be first veterebrates, came into being about 550 millions years ago. Those were extremely different from what we see today, those were without Jaw. They did not have bones in their mouth. During this 550 million years, they have taken many different shapes, and varied into some dangerous fishes. Some fishes developed electrical and chemical weapons, some took giant shape and some other developed strong jaw and sharp teeth. Since their origin, they have been adapting the varied conditions of the earth and in spite of extinct of Dinosaur, they have been maintained their existence successfully.           Parts and Features of Fish Body   Fishes have fins and tails which provide movement and balance in more...

     Introduction   There are two types of things on the earth, living and nonliving. A branch of science which deals with the study of living things is called Biology. Living things are further divided into two groups, plant kingdom and animal kingdom. On the basis of absorption of nutrients by the living organism, the organism who depends on the process of photosynthesis for their nutrition has been placed under plant kingdom, which you have studied in last chapter.            Animal Kingdom The organism who can't perform photosynthesis, has been placed under animal kingdom. Animal has been divided into two groups on the basis of back bone. Vertebrates (with a back bone) and Invertebrates (without a backbone). In this chapter we will study about the animal kingdom (vertebrates). Vertebrates and Invertebrates more...

     Housing   People at different places build different types of houses. There are same factors on which building of houses depends.   There are: The climate of the place Materials used for making houses The budget       Climate In place where climate is hot, houses have thick walls and flat roofs. Thick walls keep the inside of the house cool. Flat roofs can be used by people for sleeping outdoors. In places where it rains a lot and climate is hot and damp, houses are built on stilts. These houses, built a few feet above the ground on raised platforms, remain safe from floods. The sloping roofs of housed on hills do not allow rainwater or snow to collect and make the houses damp and cold. Most houses in cold areas have fireplaces to keep the more...

     Types of Crops   Crops are plants that are grown to satisfy the various needs of people and animals like food, shelter, clothing etc.            Food Crops These crops are cultivated for the purpose of food. i.e. to produce carbohydrates that give energy to the body. These can also be called as energy giving crops. Crops food are the main sources of proteins and vitamins. These are rice, maize, wheat, oat, barley, vegetables, fruits etc. Rice crops are grown in areas with high rainfall and in clayey soil. Maize crops are grown in warm places and sandy soil etc. Wheat is grown in sandy irrigated soil of Haryana and Punjab,                                    more...