All metric units and prefixes have a symbol (almost always one letter). Since there are units and prefixes that use the same letters it is VERY important that you realize that capital letters are NOT the same as lower case letters. In other words M has a very different meaning than m.
The metric unit of mass is the gram. This is approximately the mass of a small paperclip or a newly minted dollar bill. The abbreviation for gram is g.
The metric unit of length is the meter. A meter is roughly the same distance as a yard. The abbreviation for meter is m. It is important that this be a lower case m, as capital M has a very different meaning in chemistry.
The metric unit of volume is the liter. This is, rather obviously, the amount of soda in a one liter soda bottle. The abbreviation for liter is L. Some texts (and people) use a lower case L, but when typed it is difficult, if not impossible, to distinguish between a lower case L and the numeral one so we will use a capital L exclusively in this text.
The metric unit of time is the second. This is exactly the same as a second in the English system. The abbreviation for second is s.
Temperature is measured in degrees Celsius. A degree on the Celsius scale is larger than a Fahrenheit degree. To begin to get a feel for the Celsius scale you should know the following relationships: -40oC = -40oF, 0oC = 32oF (the freezing point of water), 37oC = 98.6oF (normal body temperature), and 100oC = 212oF (the boiling point of water). A room is that is 23oC is nicely comfortable, Any temperature below 0oC makes a bitterly cold winter day and a 35oC day is horribly hot. We will discuss another temperature scale later in the text.
There are other units for measurements such as energy, force, pressure, etc. Those that are relevant for this text will be addressed as needed.