Tell me Why?? ~ Sites for Kids - PowerPoint Presentations for Kids

Saturday, January 8, 2011

Tell me Why??

tell me why

Slide 1:

Tell me Why?

Slide 2:

Why do we sweat when our bodies start to overheat? 
Perspiration or sweat is your body’s way of cooling itself . We sweat in order to keep the body at its normal temperature , which is 98.6 F. If we lose this bodily function , we could suffer from heatstroke in hot weather . Did you know that in very hot weather human beings sweat several litres in one hour.

Slide 3:

Why is the Sun spotty? 
Some parts of the Sun’s surface are cooler than the rest of it. These cooler parts appear darker than the rest of the Sun, like spots on its surface. They are called sunspots.

Slide 4:

Why do stars twinkle? 
Stars twinkle when we observe them ‘from the surface of the earth’ because we are viewing them through different layers of turbulent (swirling) air and temperatures in the Earth's atmosphere ‘the mass of air surrounding the Earth’. This therefore means, the Earth's atmosphere is made up of several “layers” of moving air, each having different temperature and density.

Slide 5:

Why do we blink our eyes? 
We blink our eyes to lubricate and filter them. Blinking our eyes, to keep them from drying up, and to prevent foreign matter from entering and irritating our eyes. Blinking also coats the eyelid and eyelashes with the lubricant it secretes, to prevent them from drying up. Yet another benefit of blinking is to shield the eye from foreign bodies. Our eyelashes- short, curved, hairs- attached to the eyelids, serve as dust catchers.

Slide 6:

Why do we yawn?
 Yawning is an involuntary action that causes us to open our mouths wide and breathe in deeply . We yawn when oxygen levels in our lungs become low. Studies show that during normal breathing we don't use anywhere near lung capacity. The air sacs or alveoli needs fresh air or else they tend to stiffen up a bit. Therefore it is believed that the brain prompts the body to either sigh or take a yawn to get more air into the lungs.

Slide 7:

Why do you cry while slicing onions? 
Onion cells contain a chemical compound that contains sulfur. When we slice onions the cells rupture and react with the enzyme outside the cells. This reaction produces molecules which react with the moisture in our eyes (forming sulfuric acid ) which in turn causes an irritating sensation. This makes our eyes water .