Downtown Campus Biology > Biology 181 > Lesson 1 Activities > Scientific Measurements- Page 4

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

• liter (l)
• milliliter (ml)

Take a look at the graduated cylinder

Although the basic unit of volume is the liter (l), a liter is a little big for measuring most volumes in the biology lab. So we use the milliliter (ml) for most measurements. This particular graduated cylinder holds 100 ml.

How much is a milliliter?

If we take a cube that is 1 cm x 1 cm x 1 cm and fill it with water, the volume of water is 1 ml. In other words, 1 cm³ = 1 ml. Keep in mind that 1 cm³ is also called 1 cubic cm, or 1 cc for short. So the next time the doctor gives you an injection of 5 cc, you will know that is the same as 5 ml.

How do you measure volume with the graduated cylinder?

With water in the cylinder, you look at the cylinder from the side, at eye level with the water. The water line is curved, with the lowest point in the middle. This curve in the water line is called the meniscus, and is caused by the tendency of the water molecules to stick to the sides of the cylinder. When you read the volume in a graduated cylinder, you read it at the BOTTOM of the meniscus.

Let's try reading the volume (in ml) in this photo of a graduated cylinder, and then convert the measurement to liters.

• The volume of water is 58 ml.
• To convert 58 ml to liters, divide by 1000 (which means moving the decimal point three places to the left). 58 ml = 0.058 l.
• Record these numbers on Question #5 on your worksheet.

Here is the “columns conversion chart” again.

Here's the staircase for 0.058 l

To convert 0.058 l to milliliters, move the decimal down the staircase:

You can see that 0.058 l = 58 ml.

If you want, copy the columns chart or the staircase under Question #6 on your worksheet.

Click here to continue

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