G4-Measurements Lower Level- 02


Imagine talking to a friend and only being able to hear every other word. What sense could you make of the talk? Imagine now this was two scientists trying to talk. What if they were not missing every other word but key details about measurements? What kind of problem would this cause for the scientists?

From gallons of gas to cups of sugar, everything gets measured. When scientists measure an amount, they always show the measurement with units. Meters, kilograms, and degrees Celsius are all common units used in science. A scientist may measure the length of a fish as 17 centimeters (about 6.69 in). He may write down its mass to be 734 grams. The temperature of the lake where the fish was caught may be 13 degrees Celsius. The scientist would write these amounts and units carefully in his journal.

Can you think of anything that does not have a unit connected with it? What if the scientists wanted to tell how the fish looked? He may say the fish had whiskers or had red stripes down its side. Certainly not all observations need to have units. Observations such as color or shape do not include them because they are not numbers. Saying you have “one” or even “seven” does not provide much information. It could mean one brother, one pencil, or one dollar. By not giving the units, your statement is not whole.

A car tire needs a pressure of 32 pounds for enough growth. The speed limit may be stated on a sign as 55 miles per hour (MPH). These units all have one thing in common. They are all based on a system of measurement called the ‘US Customary System.’ Like any system of measurement, our system of measurement was put in place to normalize units.

Normalized units were created for the purpose of buying and selling. Would you purchase an item if you did not know the contents? That is the risk taken if we did not have normalized units.