How to make a paper house for dasara doll decoration

Step 1 : Take an A4 size sheet or a color cardboard paper and draw the picture as shown below with pencil and scale. The picture should be drawn to scale along with flaps.

Step 2 : Draw doors, windows, roof tiles, window curtains and other things. Colour the house.

Step 3 : Cut the house picture and fold along the lines. Apply glue to the flaps and firmly stick it. Paper house is ready.

Match-stick Top

Playing with tops is a lot of fun. Making them is even more exciting. Lets make some colorful tops and play with them.

Things needed : matchstick, hard cardboard/cork/bottle cap, colors, scissors

How to make

Step 1 : cut a circular piece of cardboard. Make a small hole in the center.

Step 2 : Insert a matchstick (you could also use a short pencil ) into the hole and spin it.

Step 3 : For making color tops, divide a piece of circular paper into many sectors and color them. To understand the concept of mixing of colors or "persistence of vision" do the following.

• Color the top with alternate blue and yellow colors and see how your top turns green as it spins. Similarly yellow + orange = red. Try mixing different colors and make a color chart of your own.
• Make 7 sectors and color them with rainbow colors (VIBGYOR) and see how the top turns white when it spins. This is because white light is made up of 7 colors of the rainbow; and when these colors are mixed together, we see white color.

 Video of spinning Matchstick Top

Tricks of Vision

Here are some amazing optical tricks which children can learn and try it out with their friends.

The Book Rack Trick

Is segment AB shorter than  segment XY or are both the segments equal?

If you have said AB is shorter than XY then you were wrong. Both AB and XY are of the same length. It is the optical illusion that makes us think that segment AB is shorter than segment XY.

How to draw the book Rack?
Draw two parallel lines of equal length. Increase the length of the first line three times and divide the second line into three parts. Connect both the lines to form a book rack structure.

Now complete the book rack as shown above. You can cut 2 equal straw pieces of length AB and place them on AB and XY respectively. Then ask your friends if straw AB is smaller than XY or are they equal and see what they answer. Explain the trick to your friends too.

Similar Optical illusions

Here is another optical illusion where segment AB appears to be shorter than BC, although they are equal in length. 

 Arc A appears to be smaller than arc B, although they both are of the same size and shape.

Tower of Brahma OR Tower of Hanoi Problem

The 'Tower of Brahma' or 'Tower of Hanoi' is a very interesting problem. There will be a stack of rings on a rod with the largest one at the bottom and the smallest at the top. All the rings in the stack have to be moved to another rod such that the order of the rings remain the same (biggest at the bottom and the smallest at the top). A third rod will be provided for the transfer. Find out the minimum number of moves needed to transfer the stack from one rod to another.

Rules to be followed during the stack transfer are :

1. Only one ring can be moved at a time.
2. Move is allowed only if a smaller ring is placed on a larger ring.

Kids Play

This is a problem that needs logic and calculations for college students but its some exciting fun time for kids. They really enjoy moving the stacks from one rod to another. Parents just need to tell the rules of the problem and see how your little one engages himself/herself in the puzzle.

 
Solution
number of rings        minimum number of moves
        1                     1
        2                     2x2-1
        3                     2x2x2-1
        4                     2x2x2x2-1
        5                     2x2x2x2x2-1

Video : Moving a stack of 4 jar lids from one plate to another with a minimum number of moves.

Pinhole Camera

        A solar eclipse occurs when the moon passes between the sun and the Earth. During an eclipse the Sun, Moon and Earth are in the same line. The Moon partially, or fully blocks the Sun. A total solar eclipse occurs when the Moon completely covers the Sun's disk.
        It is very dangerous to see the sun through naked eyes or even any kind of filters. During Eclipse time it would be a wonderful experience if only you could see how the moon covers our sun partially or completely. To make it possible, we need to know how to construct a pin hole camera so that we can safely see the image of the sun on a butter paper.

How to make a pinhole camera

Things required : a long tube about 1meter in length, pin, butter paper / oil smeared paper, a shoe box/ wide box, a sheet of dark paper.

Step 1 : Cover one end of the tube with dark paper and prick a pinhole in the center. Cover the other end with butter paper so that we can see the inverted image of the sun.

Step 2 : make a circular hole in the box so that the tube fits in tightly. This box acts as a protection to the eye and also increases shade so that the pinhole image looks more brighter.

Observing partial Solar Eclipse that occurred in Bengaluru in 2009 through pinhole camera.

Ball Bearing Experiment

        A machine that works requires energy. Part of the energy is lost due to friction. Friction is a force that opposes motion. It is caused by the moving parts of a machine when they rub against each other. Reducing friction allows machines to run smoothly and efficiently and consume less fuel and energy. Bearings are supports that reduce friction. They help a moving part to roll rather than rub on its support. It consists of small metal balls over which the rotating part rolls over.

Ball Bearing Experiment

Let us build a simple ball bearing and see how it enables objects to spin easily.

Things we need

2 jar lids (one of which closely fits into another), marbles/ metal balls, pencil, clay, A wooden block, sticky tape.

Step 1 : Stick the smaller jar lid upside down on a wooden block.

Step 2: Place two equal blocks of clay on the ends of the pencil and stick the middle of the pencil to the larger lid.

Step 3 : Put the larger lid over the smaller lid and spin it sharply. Note how long it spins.

Step 4 : Remove the top lid and put marbles into the smaller lid. There should be enough marbled to form a ring and they should be able to move freely. Now replace the larger lid over the smaller lid and spin the pencil sharply. Note how long it spins. 

Observation

We observe that the pencil spins faster and longer when the two lids are separated by marbles. Thus the marbles or metal balls act as ball bearings and reduce friction between the rotating top lid and its support. Here is an example where ball bearing is put to practical use.

 Ball Bearing Experiment Video

How cable car works