Downtown Campus Biology > Biology 181 > Lesson 1 Activities > Scientific Measurements- Page 2

Measuring Length, continued

The commonly used units for measuring length (and the only ones we need to know right now) are:

• kilometer (km)
• meter (m)
• centimeter (cm)
• millimeter (mm)

Let's take a closer look at a meter stick.
The meter stick is 1 meter long. (What a coincidence!) A meter is divided into 100 cm. On the meter stick, notice the numbers 1 through 10, and then by tens to 100. Each number represents 1 cm.

Each centimeter is further divided into 10 mm. Therefore, there are 1000 mm in a meter. Each tiny little line on the meter stick represents one mm. (If you don't believe me, count them! There should be exactly 1000 little marks on the meter stick.)Notice that a mm is about the thickness of a penny. (There is a penny in your kit, of you want to take a closer look.)

The other unit you need to know is the kilometer. Imagine 1000 of these meter sticks laid end to end. How long is that? 1 km is a little over a half mile (Think of the road signs on I-17 south towards Nogales, if you're familiar with that.)

Let's try measuring something.
In the kit, you have an unsharpened pencil. We will measure the length of that pencil. Lay it on the meter stick, as in the photo.

The pencil goes past the 10 cm mark, and then another 8 cm past that, for a total of 18 cm. Beyond the 18 cm mark, it goes up to the ninth little line, so the total length of the pencil is 18.9 cm.

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