This is what I did!

Taken from here
I remember I did this in my primary school. Part of the "rainbow" theory in science subject.

Disappearing Color Science Experiment

This science experiment is a lot like magic. Watch the colors disappear right in front of your eyes!

Tools

Paper plate
Pencil
Ruler
Markers (purple, blue, green, yellow, orange, red)
String or yarn

Procedure

1. Divide your plate into six even sections using your pencil and ruler.

2. Use your markers to color each section one of the colors of the rainbow.

3. Use your pencil to punch two small holes in your plate, each about 1cm from the center. Cut off the excess plate to leave just your colored circle. Lace your string or yard through the holes as shown.

4. Hold one end of the string in each hand so that the color disk is in the middle. Wind up your your disk by turning while you hold the string. You may need the assistance of another person. When the string is wound up tight pull both hands away from each other so that your colored disk spins quickly.

What Happens?
The color will begin to blur together and will eventually appear to disappear or turn white.

Why Does This Happen?

The disk need to be spun quickly in order to create the disappearing effect. At the fast rate of speed your eyes are not able to differentiate each individual color, you create a blurring effect with each color overlapping. Therefore, your brain perceives this combination of color as white light.

Extension
Try this again, but use only two primary colors on your disk. What do you think will happen?

Another one that I did and love to do is:

The Secret Messages

Taken from here

I remember to did this after I read the "Famous Five " and "the Mysteries series"by Enyd Blyton.Where they need to send "secret" messages without letting the enemies of knowing it. So I pretend to be one of the detective and tried to pass the message to my brother. I even learn how to come out from a locked room! hahah... That time we didn't have Nintendo , PS2, PSP, PS3.PC, or many TV shows yet, so we must be pretty creative to entertain ourselves!

Do you have a budding detective at home? Does your curious first grader have a keen sense of observation? To develop a strong scientific thinking foundation, you'll want to provide opportunities for your child to explore scientific process skills such as using her senses to describe observations.

At school when your child learns about scientific concepts, she makes observations, she is encouraged to experiment with various materials and allow the materials to interact with other thing, and then make note of any changes. These are some of the fundamentals of scientific thinking and the basis for the scientific method, which she'll learn in the years ahead. Here’s an exciting experiment you can do with her at home that will continue to reinforce what she is learning at school, while dazzling her with mystery at the same time!

You Will Need:

• Lemon juice
• Cup
• Paintbrush
• White bond paper (This is white paper of 24 pound weight usually found at office supply stores.)
• Iron NOTE: Only an adult is allowed to use the iron!
• Newspaper

What to Do:

1. Allow your child to squeeze the juice of one lemon into a cup.
2. Tell your child to think of a secret message that she wants to write to a friend or family member.
3. Then have your child dip the paintbrush in the lemon juice and paint her message on the white bond paper.
4. Allow the paper to dry completely.
5. Once the paper is completely dry, your child will need to place the drawing between several sheets of newspaper. Then iron the paper until your brown design appears.
6. Allow your child to examine the secret message. Allow her to describe how the message looks different after it had been ironed, compared to how it looked before you ironed it. Then let your child deliver her secret message to her friend or family member.

Did You Know?

When the message is painted with lemon juice, it dries in an invisible design. Then when the iron heats the lemon juice markings, the natural sugar in the juice becomes activated and burns, turning into a brown carbon substance. The burned, browned juice then appears as the secret message.

So what do you think? do these experiment bring back your childhood memories ? And by the way I LOVE Enyd Blyton's book. The Famous Five, The mystery , The Secret Seven,St. Clare, The Mallory Towers! Oh how I love to buy those books to be pass on to my girls!

What is your favorite childhood books? And what is your favorite childhood activities?