The Earth is divided into 24 time zones. If you don't understand that, have an adult show you on a globe or a large map of the world. Remember that fact. Presents are delivered between 10 PM on Christmas Eve and 6 AM on Christmas Morning – that is eight hours.
Now take seven of those eight hours and simply put them in your pocket for a minute. That leaves one hour in each of the 24 different time zones. Now add the seven hours from your pocket to the 24 hours and you have 31 hours available for Santa to make his deliveries. That's the science part of it.
If you look at a globe you will see there are large parts of the world that is ocean and where there are no children.
The rest of the answer comes from the fact that reindeer fly very, very fast – about 650 miles per minute.
The answer to this question is a combination of science and Christmas magic. Reindeer can run very fast. Even when they are only one day old they can run faster than a grown man.
Next, unlike most reindeer, Santa's reindeer keep their antlers until after Christmas. Most reindeer lose their antlers earlier in the winter. It is these antlers that help the reindeer to fly, acting sort of like an airplane wing to disturb the air so they can get off the ground.
Remember, scientists today still do not know how a bumblebee flies. According to scientists, bumblebees should not be able to fly. But they do. Well, scientists don't know how Santa's reindeer fly. But they do.
Many years ago a group of people came to talk to Santa Claus. They were from the United States Federal Aviation Agency (FAA) but they represented every country in the world. These people are responsible for the safety of all the airplanes in the sky. They told Santa they were very worried about him being hit by an airplane because there are so many more of airplanes now than there used to be.
These very nice people wanted to help Santa fly his sleigh safely. First they gave Santa a special radio to put in his sleigh so he can contact them and tell them when and where he is flying.
Next they arranged so that around the world there are special airports with a special secret building reserved just for Santa's sleigh and reindeer. Now when Santa flies into a town before Christmas, he radios ahead to let them know he is coming. Then he lands at one of the special airports and the people there open the secret building for the sleigh and reindeer. Then someone either loans him a car or drive hims where ever he needs to go. And they always make a big fuss about the reindeer – petting them, feeding them, enjoying them. The reindeer really enjoy it too. But they fly slower going home because of all the junk food they ate.
On Christmas Eve, Santa flies all over the world and from house to house. However a group called NORAD tracks Santa wherever he is at and advises airplanes on how to stay out of his path so that he can fly safely. You can follow Santa on the internet at http://www.noradsanta.org/.