> Scientists called physicists use a lot of mathematics in their work. > As you can see, they use letters and symbols more often than numbers. On a desert in New Mexico, a large number of people...
Sun clocks
A clock certainly seems nothing like a ruler. Yet, a clock and a ruler do the same kind of job. They both measure something. A ruler measures length and a clock measures time. People of long ago...
Measuring time by the stars
People of long ago lived out of doors most of the time, so they were used to seeing the stars at night. And they knew that the stars moved across the sky during the year. Because the stars always...
Suns and moons, winters and summers
If you want to know what time it is, you look at a watch or a clock. If you want to know the date, you look at a calendar. A clock measures time during a day. It lets you know when to turn on a...
Doing things by tens
About two hundred years ago, there was a big change in the country of France. The French people were being badly mistreated by their king and the nobles. So, the people rose up and got rid of them...
Making things even
There was one trouble with the way people first measured things with their arms, hands, and feet. Some people have longer arms, bigger feet, and wider hands than others. If you and your father each...
Feet and fingers, hands and arms
On a hillside, near the entrance to a cave, a woman sat busily at work. She wore a dress made of animal skins, and around her neck were strings of beads made of sea shells and animals' teeth. The...
Sharing birthdays
What would you do if you were invited to two birthday parties on the same day? Well, you would probably go to the party of the person who had asked you first. That would be the fair thing to do....
A gift from Arabia
The numerals now used by Arabic-speaking people are not much like the ones we call Arabic numerals. Only the 1 and the 9 are like ours, as you can see in this multiplication table from a book written...
Stop at ten
Before people began to count, they probably had no name for any number but one. Suppose a hunter wanted to tell about a small herd of four to six deer he had seen. He might just say it was a "hand"...