Grow a Garden of Mold 
Take a wide plastic jar, or a wide glass jar or a rectangle or a square, or even a round container. Put some bread pieces, vegetables pieces. meat pieces, wood, metal, rope, paper, plastic, cloth etc in it. Pour some water on it and cover the container with a plastic bag or sheet so that its humidity should not go out.

After a few days you will see several kinds of mold on different kinds of materials. You may keep it for one year, then see it how different it looks and how it smells. In fact it is the humidity in the environment which is the main cause of this mold. That is why in those regions where there rains a lot, most things, even shoes, get mold on them. Not to get mold on them, you must keep them in sunshine for sometime at time to time so that they are dry.

Can you make your room cooler by leaving the door of your refrigerator open?
No, because refrigerator throws its own warm air outside, so the temperature of the room will not be affected by leaving the door of the refrigerator open.

Two Balloons: One Floats, Another Immerses
There are two balloons full of water. You want to make one balloon immersed in a hot water tub,  while the other one floating on the same water? What will you do? Fill one balloon with warm water, and the other one with cold water. The cold water balloon will immerse in the water, while the hot water balloon will float on the water. But for how long the cold water balloon will be immersed in hot water? Until its water becomes warm, so that it becomes lighter enough to float on the water. Later the cold water balloon will also come up.

Throw Your Golf Ball Farther Than Usual
If you want to throw your golf ball much far than usual, then play golf in mountains. Why? Because there the air is lighter, so it will go farther than it goes in flat plains.

Giant Dry Ice Bubble Experiment
Distilled water, Dish detergent, Glycerin, Dry Ice, One bowl, A cloth strip which could go round the bowl rim
Pour 1 cup of Distilled water - (you may use your big glass  measuring cup)
Pour 5 Tablespoons of Dish detergent
Pour 4 Tablespoons of Glycerin ---- STIR WELL

Put the Dry ice in a big bowl and pour some water on it - it will start foaming up and will come to the brim of the bowl
Wet the cloth strip in the solution of water, detergent and glycerin
Just wipe the brim of the bowl to stop water overflowing the bowl
This wiping will stop water to flow out of the bowl and make a big bubble
It will go on increasing and at last will burst out.....