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.