When a liquid is placed in a piece of laboratory equipment such as a graduated cylinder, buret, or a beaker, you will notice a "curve" at the surface of the liquid. This curve is known as the meniscus. As the diameter of the container decreases, the meniscus becomes more pronounced. The meniscus may be convex (curving upward) or concave (curving downward). Most of the time you will find that the meniscus is concave. The most notable exception is the meniscus that forms from mercury.

When taking measurement readings it is important that the reading is done properly. The following rules must be adhered to:

Read the meniscus at eye level. Do not read the meniscus from above or below eye level. Significant measurement errors may occur

Read the bottom of a concave meniscus and the top of a convex meniscus.

The bottom of this meniscus is between 6.0 and 6.1 mL. The correct reading is 6.07 mL.