Wayne Little, age 11, of Niagara Falls, Ontario, Canada, for his question:

What is the history of the inch unit?

Noah never mislaid has yardstick. He measured his carpentry by the distance between his elbow and fingertips. This built in unit was the cubit and it equalled about 18 inches. If Noah was an average sized man, his ark was 450 feet long. Early carpenters also used other parts of their bodies as measuring units. The foot unit was the length of a man's foot from heel to toe. The yard was the distance between his nose and the finger at the end of his outstretched arm. The inch was the width of his thumb or the distance between the tip of his forefinger and its first joint.

Ages ago, people saw ratios in these bodily units of long measure. There were about 12 inches in a foot and about three feet in a yard. This was useful to know, but the units themselves were unreliable. They varied from person to person. A big man's foot may be five inches longer than a small man's. So experts met to decide on standard measuring units. In modern times, international experts figured the old units from the more reliable meter. The up to date inch measures 2.54 centimeters or 25.40005 millimeters.