Math Magic

Isitaclosedshapewith6sides?_______ IsitthesameastheonemadebyRohini?___________ Istheresomewaytosayin whatwaytheseshapesaredifferent? h Mohini tried again but got different shapes. Guess and make twomoreshapesMohinicouldhavemade. MohiniisnowtiredoftryingandasksShailawhattodo. If you ask for the angles that the Oh! So let us lookmatchsticks make at the for the angles. corners, you can do it. h Look at the angles marked in these shapes. Can you seethedifference? Rohini Mohini It is important to encourage children to think about the way in which shapes can differ even when the number of sides is the same. This will help them to get a sense of how angles determinetheshapeofapolygon. 17 4) How many different shapes can you make by changing the anglebetweenthematchsticks ineachofthese?Try. c)a) b) 5 matchsticks4 matchsticks 8 matchsticks e)d) 7 matchsticks 10 matchsticks MatchstickPuzzles 1) Make8trianglesusing6matchsticks. Try! 2)Take8matchsticksandmakeafishlikethis. Now pick up any 3 matchsticks and put them in such a way that the fish now starts swimmingintheoppositedirection.Didit? 3) Using 10 matchsticks make this shape. Pick up 5 matchsticks and put them in such a waythatyougettheshapeofahouse. If you have not been able to solve these then look for the answers on page 29. 19 AngleTester Let us make an angle tester. How do we make You also have an angleequal angles? tester in your geometry box. It is called a divider. h Cuttwostripsfromacardboardsheet. h Fix them with a drawing pin or such that both the strips canmovearoundeasily. Rohini and Mohini went all around with the angle tester to look fordifferentanglesintheirclass. RohinitestedtheangleoftheMathsbookandthepencilbox. Look at the tester. It has opened like the letter L. This is a right angle. We write it as L. 20 2) Sukhmanmadethispicturewithsomanyangles. Usecolourpencilstomark. h rightangleswithblackcolour. h angleswhicharemorethanarightanglewithgreen. h angleswhicharelessthanarightanglewithblue. 3) Draw anything of your choice around the angle shown. Also writewhatkindofangleitis.Thefirstoneisdone. Less than a right angle 22 Activity a)Takeasquaresheetofpaper. b) Folditinhalf. c) Folditoncemoreandpressit. d) Openthelastfoldsothatthesheetisfoldedinhalf. e) Takeonecornerandfoldittomeetthedottedline. On the paper you will find lines making a right angle, an angle lessthanarightangleandananglemorethanarightangle. Lookforeachoftheanglesandmarkthemwithdifferentcolours. Activity — Angles with your body Can you make these angles? a) Arightanglewithyourhand? b) Ananglelessthanarightanglewithyourleg? c) Ananglemorethanarightanglewithyourarm? d) Ananglemorethanarightanglewithyourbody? Try them out. It's fun! Draw them in your notebook usingstickdrawingslikethese. 23 AngleGarden My angle dance shows the way! When I see flowers for making honey, I want to tell other bees. To show them the way I start dancing. My dance shows the angle between the sun and the flower. Activity Collect some leaves from the garden. Colour each leaf and print it. Look at the angles on the leaves. Whichofthemaremore/lessthanarightangle? Hey! Look at that bird. Its beak has an angle less than a right angle. 24 h Lookforthebirdswhichhavebeakswithsmallangles. h In the picture mark angles between the two branches. Which twobrancheshavethebiggestangle? Angles in Names In my name there are 11 right angles. There are also 10 angles lessthanarightangle. h Write3namesusingstraightlinesandcountthe angles. Name Number of Number of angles Number of angles right angles more than a right angle less than a right angle Activity a) Put 10 Math-Magic books on top of each other.Keeponebookslantingtomakeaslide. b) Nowdothiswithsixbooks. h RFromoll a ball from the top. which slide does the ball roll downfaster? h Whichslidehasthesmallerangle? 25 Thesearetwo slidesinapark. h Which slide hasalarger angle? h Which slide do you think is safer for the little boy? Why? Changing Shapes h Things you need — used (or new) matchsticks. Piece of rubber tube used in cycle valves. i) Clean the black end of the matchsticks. ii) Cut small pieces of the tube (about 1cm long). iii) Push two matchsticks into each end ofatube piece. iv) Add more matchsticks to form a triangle. Now make these 4, 5, 6 sided shapes by using tube pieces and matchsticks. a)b) c) h Find out how many angles are there in each of these shapes. Markthem. Nowpusheachshapedownwardswiththetipofyourfinger. Doestheanglechangewhenpusheddownbythefinger? h Findoutandwriteyourresultsinthetablegiven. Shape Change in angle Yes/no 27 Shapesand Towers Lookfortrianglesinthepicturesbelow. h From the activity ‘Changing Shapes’ can you guess why trianglesareusedinthesetowers,bridgesetc? h Lookaroundandfindoutmoreplaceswheretrianglesareused. Angleand Time Zeenat, your watch does not have digits. How do you read time? h There are many times inaday when thehands of a clockmake arightangle.Nowyoudrawsomemore. Triangles are shapes which are strong and do not change easily when pressed. In fact, childrencanalsoobservehowdifferentshapesaremadestrongerbyusingdiagonalbeams (likeinthebridge) whichdivideshapesintotriangles. 28 DegreeClock AppuandKittuareplayingcarromboard.Appuhitthestriker. Hm Hm........ It comes back at the same angle. h In the picture three points A, B and C are shown. Draw a line to show from which point Kittu should hit to get the queen._______ If you want, you can measure the angle in degrees using a degree clock. Degree is written as º. A B C 30

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