MATCHSTICK MODELS AND OTHER SCIENCE EXPERIMENTS By Arvind Gupta email: [email protected] CHILDREN'S WORLD Children learn by doing. They learn a great deal by tinkering & pottering playing with or simply messing things around them. It is in these free acts that children familiarize themselves with the properties of a lot of common things and everyday phenomenon. Children love to do things. They are by nature eternal explorers. The most commonplace and insignificant phenomenon from the adult point of view intrigues them - be it the rustling of leaves, the chirping and flight of the sparrow, the falling of water from the tap, or the spewing of smoke from an extinguished matchstick. All these capture, excite and enrapture a child's imagination. To a child no object is insignificant. Everything is to be tasted, toppled, turned and tested in order to test it. Every event, happening and thing warrants attention and further exploration. The humblest looking object becomes sources of unending intrigue and joy. An ordinary matchbox becomes a 'magic box'. It transforms into a rattle when shaken. Its drawer floats like a boat in water. The matchbox is a trunk, box, wagon, tow-car, tiffin box and a secret cache all rolled into one. Every child has an assortment of odds, bits and trinkets - shoe polish tins, broken pens, discarded cardboard boxes, used bottles and few bangles and other throwaway junk, which constitute her/his most cherished treasure trove. Children are very imaginative. The whole world is art for them. It is usual for them to construct castles in the sand and see outlines of animals and birds in pebbles and stones. Fallen twigs and blades of grass, the arrangement of leaves, spilled ink on the door or the changing colour palette of the sky are all fascinating patterns and designs for the child. But slowly this innate curiosity and creativity of the child is squashed by the authoritarian and patriarchal structures of the family, school and society Thus, as a child grows up, the artist within her/him goes to sleep. Art, which earlier embodied the whole world is now reduced to the frame of a canvas painting, murderously hung from the wall. This booklet attempts to give a glimpse of some of the experiments and toys designed as part of the Hoshangabad Science Teaching Programme. Intensive use is made of things which are commonly available and with which the children are familiar. Many of the experiments were designed, often with the help of village children and teachers, in response to the dismal poverty existing in most village school. Today science has become synonymous with fancy glassware and expensive laboratories. The learning of science is being equated with an ability to mug up definitions and formulae. But is this good science? Science, in essence, is a viewpoint – a worldview, an ability to critically examine phenomenon. It is an ability to see patterns, structures, sequences, trends, and commonalties, regularities and generalities - in short, an ability to perceive and discover an order in the universe. From this point of view every object is a piece of science apparatus and every child is a budding scientist. To explore answers to her/his questions is the basic right of every child. The present day school's attitude towards children can be summed up as follows: We give them solutions and keep the confidence to ourselves. We give them memory but keep the thinking to ourselves. We give them marks and keep the knowledge to ourselves. The pity is that we have never asked the children real problems, and whenever we did, it has been with the intention of hearing to the same regurgitated solutions that we gave them. This must end. MATCHSTICK MODELS Any mecanno, even of the most expensive sort, when stripped of its and fancies essentially reduces to a few building blocks and couplings. These blocks and couplings can be joined together in a variety of ways to create an an array of different structures and configuration: The matchstick mecanno uses matchsticks as the basic structural members and bits of cycle valve tube as the joints. Cycle valve tube is sold by weight in cycle shops. A 100-gms packet costs Rupees 15, and contains about 16 meters (or 50 feet) of valve tube. JOINT - OF - TWO Cut about 15-cm long pieces of the valve tube. Scrape the sulfur from matchstick heads with a blade. Push one end of a matchstick through a valve tube piece. You’ll find that the matchstick slides snugly in the valve tube. Push a second matchstick through the other end of the valve tube piece. The ends of both the matchsticks should touch head-to-head inside the valve tube. This is a joint of two matchsticks, or simply a joint-of-two. The flexible joint-of-two can be used for illustrating angles – acute; right; obtuse and straight angles. Three matchstick and three valve tube pieces in a row can be looped together make a triangle. As the matchsticks are the same lengths the triangle turns out to be equilateral - with all sides equal. All the angles in this triangle are equal and measure 60 degrees. Other shapes like isosceles triangle, squares, rectangles, pentagons, hexagons and octagons can be made by joining together more matchsticks and more valve tube pieces. A whole range of polygons can be made in this way. DIFFERENT PATTERNS Make several triangles, squares, rectangles, pentagons and hexagons. Now arrange these shapes into different patterns. You can discover several new patterns on your own. PATTERNS IN NATURE Nature provides us with a whole array of patterns. Often putting together a few basic shapes in a definite order makes these patterns. We get a glimpse of nature's designs in the honeycomb, arrangement of flower petals, the symmetric patterns on a butterfly's wings and a myriad other places. Some examples of human made patterns are the fixing of floor tiles, and the traditional 'rangoli.' RIGIDITY OF A TRIANGLE Try pressing a pentagon between your thumb and the middle finger. What happens? The pentagon distorts into a boat shape. If you hold it with both the hands and flex it, then it shakes. It is a dancing shape. Now press the opposite corners of a square. What happens? The square is unable to resist the pressure. Its right angles give way and distort into a rhombus, or a diamond shape. Finally, try pressing or shaking the triangle. What happens? The triangle does not budge at all. Its shape remains intact. In short, a triangle remains a triangle. The triangle is the only rigid shape. All other shapes like hexagons, pentagons, squares and rectangles are wobbly and shaky. How can the square be made rigid? Insert a long babool thorn (or a long needle) through two diagonally opposite valve tube joints of the square. The thorn divides the square into two triangles. The triangles make the square rigid. How can the 'dancing' pentagon be made rigid? TRIANGLES IN USE The triangle does not shake. The triangle does not distort. The triangle is the most rigid shape. This rigidity of triangles makes them very useful in making houses, bridges and a number of other structures, which we use, in daily life. Most roof trusses of village houses are made of bamboo and wooden beams. The bamboos and beams are always arranged in triangles. The trusses are never arranged in squares, pentagons or hexagons. What would happen if the roof truss were divided into squares? The square truss will not be able to support the weight of the roof. Because of the weight of the tiles, the squares will buckle into diamond shapes and the truss will collapse. Similarly, the structural members of railway bridges and electric towers are divided into triangles. The triangles make them rigid. JOINT - OF - THREE Pierce a hole in the valve tube joint-of-two by poking it at right angles with a babool thorn. Insert a third matchstick (slightly sharpened at the end) in this hole. This is a JOINT-OF-THREE, or simply a “T” joint. Take the equilateral triangle and poke holes in its valve tube joints with a babool thorn. Now insert the three matchstick ends of the 'T' joint in the holes of the triangle. The “T” joint and the equilateral triangle thus put together form a new structure. It has 4 corners, 6 edges and 4 distinct surfaces. All its surfaces are equilateral triangles. As triangles are rigid so, a structure built entirely of triangles must be very rigid too. And indeed it turns out to be true. This structure is called a TETRAHEDRON and is one of the most fundamental structures found in nature. In a similar manner join together two separate triangles using three matchsticks to make a PRISM. Joint two separate squares with 4 matchsticks, to make a CUBE. Make many more structures using the joint-of-three. RIGIDITY OF A TETRAHEDRON The tetrahedron is the strongest structure found in nature. It has several uses in daily life. Actually, common people have been using the tetrahedron for centuries in different kind of structures. For instance, you must have seen grain bags being weighed in the market. Often the weighing balance is suspended on a tripod of three bamboos. This tripod has a structure of a tetrahedron. Hawkers often display their wares on trays, which are kept on bamboo tripods. You must have also seen three-legged camera tripods and stools. These are just a few examples of the use of tetrahedrons. JOINT OF FOUR Cut two pieces of valve tube each about 2-cm long. Weave a babool thorn through the hole of one valve tube. The babool thorn acts as a spindle and provides rigidity to the rubber valve tube. Now, pierce the babool thorn at right angles in the middle of the second valve tube. Pull both the ends of the second valve tube so as to slightly cut the rubber in its center. Now hold the thorn vertically and rest its thick end on the door. Pull both the ends of the second valve tube (this makes the hole in the center stretch) and slide it over the first valve tube. Gently remove the valve tube cross-joint from the babool thorn. This is a JOINT-OF-FOUR, or simply a “X” joint. Fix four matchsticks in this “X” joint. Pick up the square you had made earlier. Poke holes in its valve tube joints with a babool thorn. Insert the four matchstick legs of the “X” joint in these holes. This new structure is called a PYRAMID. Its apex is a joint-of-four. Two pyramids can be put back-to-back with their square bases mating, to make an octahedron. Use six cross-joints and twelve matchsticks to make an OCTAHEDRON JOINT - OF - FIVE/SIX Make a joint - of - four but do not remove it from the babool thorn. Like the second valve tube insert a third valve tube on the first valve tube. The second and the third valve tubes are at right angles to the first valve tube. Thus we get a “H” shape. Insert a small piece of matchstick in any of the free legs of the “H”. Sharpen the end of this matchstick and weave it through the center of the other leg of the “H”. After removing the babool thorn, phase out the six legs of the valve tube star so that they are approximately sixty degrees apart. This is a JOINT-OF-SIX, or simply a “star” joint. For a JOINT-OF-FIVE, simply cut one of the legs of the “H”. Assemble twelve joints-of-five and thirty matchsticks to make an ICOSAHEDRON. The icosahedron is entirely made up of triangles and hence is very rigid.