Area and its Boundary Whose Slice is Bigger? Parth and Gini bought aam paapad (dried mango slice)fromashop. Their pieces looked like these. 6cm 5cm h Afriend of Parth and Gini showed PieceA one way, using small squares. 11 cm 3cm Suggest some ways to find out whose piece is bigger. Discuss. PieceB The lengthof pieceAis6cm. So6squaresofside1cmcanbearrangedalongitslength. The widthof pieceAis5cm. So5squarescanbe arrangedalongits width. h Altogether how many squares can be arranged on it? ________ h Sothe areaofpieceA = ________ squarecm h In the same way find the area of piece B. h Who had the bigger piece? How much bigger? Cover with Stamps This stamp has an area of4 square cm. Guess how many such stamps will cover this big rectangle. 25 Hkkjr India Encourage children to first discuss different strategies for comparing the area of things by using different tokens, stamps, etc. In Class IV they have compared irregular shapes by counting squares. In the case of rectangles they can measure the sides to see how many squaresof1cmsidewillfitinthe wholeshape. h Makeyourowndesignsof area4and6squarecm. f)Sanya, Aarushi, Manav and Kabir made greeting cards. Complete the table for their cards: Take a thick paper sheet of length 14 cm and width 9cm. You can also use an old postcard. h What is its area? What is its perimeter? h Now cut strips of equal sizes out of it. Using tape join the strips, end to end,to makeabelt. h How long is your belt?_____ h What is its perimeter _____ h Whose belt is the longest in the class? _____ Discuss h Why did some of your friends get longer belts than others? h Is the area of your belt the same as the area of the postcard? Why or why not? h Whatwillyoudotogetalongerbelt next time? Puzzle: Pass througha Postcard Can you think of how to cut a postcard so that you can pass through it? (See photo.) If you have tried hard enough and still not got it… look for the answer somewhere ahead. The aim of the belt activity is to understand that things with the same area can take different formsandalsohaveverydifferent perimeters.Whilemeasuringsides,lengthsinmmcanbe roundedoffforthis activity. People People Everywhere A)Youcanplay this gameinaground. Make two squares of one square metre each. Divide your class in two teams. Ready to play! Trythese in your teams — How many of you can sit in one square metre? _______ How many of you can stand in it? _______ Which team could make more children stand in their square? How many? _______ Which team could make more children sit in their square? How many? B) Measurethe length of the floor of your classroom in metres. Also measurethe width. h What is the area of the floor of your classroom in square metres? _______ h Howmany childrenarethereinyour class? ______ h So how many children can sit in one square metre? _______ h If you want to move around easily then how many children do you think should be there in one square metre? _______ Can you imagine how big a squareof side1km is! It has an area of ______ square km. Guess how many people can live on that. Share the Land Nasreenaisafarmerwho wantsto divideherlandequallyamong her three children — Chumki, Jhumri and Imran. She wants to divide the land so that each piece of land has one tree. Her land looks like this. h Can you divide the land equally? Show how you will divide it. Remember each person has to geta tree. Colour each person’s pieceof landdifferently. Children are not expected to do conversion of sq m into sq km or vice-versa. The aim of exerciseBisto developasenseofhowbigor smallthe unitsofsqmandsqkmare. 152 h If each square on this page is equal to1square metre of land, how much land will each of her children get? ________ squarem Chumki, Jhumri and Imran need wire to make a fence. h Who will need the longest wirefor fencing? _________ h Howmuchwireinallwillthethreeneed? ___________ A. Look at the table. If you were to write the area of each of these which column would you choose? Makea( 4). f) FindtheareaoflakeBonthedrawinginsquarecm.Whatisits actual area in square km? King's Story The King was very happy with carpenters Cheggu and Anar. They had made a very big and beautiful bed for him. So as gifts the king wanted to give some land to Cheggu, and some gold to Anar. What other rectangles can Cheggu was happy. He took 100 metres of wire and tried to make different rectangles. He madea10m×40m rectangle. Its area was 400 square metres. Sohe next made a30m×20m rectangle. What is its area? Is it more than the first rectangle? with 100 metres of wire? which of these rectangles will have the biggest area. Cheggu’s wife asked him to make a circle with the wire. She knew it had an area of 800 square metres. h Why did Cheggu not choose rectangle? Explain. So Anar also tried many different ways to makea boundary for 800 square metres of land. h He made rectanglesA,BandCof different sizes. Find out the length of the boundary of each. How much gold wire will he get for these rectangles? A 40m×20m Gold wire forA = _________ metres B 80m×10m Gold wire forB = _________ metres C 800m×1 m Gold wire forC = ____________ metres But then Anar made an even longer rectangle.... See how long! D m× 0.1m So he will get ____________ metres of gold wire!! Now do you understand why the king fainted!!! Can you make a rectangle with a still longer boundary?Imadea rectangle1 cm wide and 80000m long. Imagine how long that boundary will be!!! With that much gold wireI can become the king! 158