Science Experiments Ideas
Cold and ice
Where is the wind coming from?Moisten your finger and hold it straight up in the air. Youwill notice at once that one side of the finger is cold. This is the direction from which the wind is coming. Heat is used up when a liquid vaporises or evaporates. The wind accelerates the evaporation of the moisture on the finger and you will notice even with a weak air current the greater heat loss on the side facing the wind. Anybody who keeps on a wet bathing costume after a swim will shiver even in the heat. The water takes heat from the body as it evaporates.
Use hundred when there is a specific number, and use hundreds when you don't know or can't count how many. This rule also applies to thousand/thousands and million/millions. This skeleton is thousands of years old. This skeleton is three thousand years old.
When saying numbers, always use the singular form:
250 = Two hundred and fifty
Two hundreds and fifty
7,812 = Seven thousand, eight hundred and twelve
Seven thousands, eight hundreds and twelve
$10,000,000 = Ten million dollars
Ten millions of dollars