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...
Twenty-four hours a day
Why do we have twenty-four hours in a day? Why not twenty hours? Or sixteen hours? As a matter of fact, we have twenty-four hours in a day simply because the Egyptians did. They invented the...
The birth of the calendar
A year is a long time. So, long ago, people decided to divide it into shorter time periods. About five thousand years ago, the Sumerians divided the year into twelve "moons." Each moon had thirty...
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...
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A meter is slightly longer than a yard, or just a little longer than five Childcraft books placed flat, side by side. The word meter comes from a Greek word that means "measure." And it is from the...
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...
So many measures!
Which weighs more, a pound of feathers or a pound of gold? You probably said, "Ha, you can't fool me! A pound is a pound. They both weigh the same!" Sorry, you're wrong. A pound of feathers weighs...
Ounces and pounds
In the English, or customary, system of measurement, bread, butter, people, and many other things are weighed in ounces and pounds. But why are there sixteen ounces in a pound? And why do ounce and...
Pints, quarts, and gallons
People who use the English, or customary, system of measurement buy milk and other liquids in pints (pynts), quarts (kwawrts), and gallons uhns)---and they have a terrible time remembering that...