 Okay, we're going to talk a little bit about measurement and systems of measurement today. And measurement really tells us about the properties of something. So it can tell us about length, about width, it can tell us about mass or weight, and it can tell us about volume. So measurement tells us about the properties of an object or a substance. And the way that we use measurement is we use a unit, and a unit is a precisely defined amount of one of those properties. So a foot is a precisely defined amount of length, a pound is a precisely defined amount of weight, a gallon is a precisely defined amount of volume. So a measurement system is a group of units. So the group of units you're probably most familiar with is known as the USCS. That stands for the United States Customary System. And that one includes those units I just talked about, pounds, feet, inches, gallons, quarts. So they are the system of units, and they are the units that are customarily used in the United States. Almost all of the rest of the world uses the System Internationale. It's French, I can't quite pronounce it, but use the SI system of measurement. And that includes metric measurements. Because the rest of the world uses the SI system, that's what we use in the lab. It allows us to know exactly when we measure out a leader that that leader, when we say we have a leader of a substance in France or in Botswana, if they measure out a leader to try and replicate our experiment or understand what we did, they are measuring out that same leader. So metric system allows us to communicate with other countries who all use this system of measurement when we're talking about science and laboratory. The other reason why we might use the metric system is because it is much more systematic. So if you know your United States customary system, we have teaspoons, we have tablespoons, we have quarts, and there's two pints equal a quart, but four quarts equals a gallon. There's 126 quarts in a barrel. So there's no way of really looking at a unit in the USCS and determining how many are in another unit. So the conversion in the USCS is a little bit non-systematic. In the metric system, we'll talk a little bit about metric prefixes in another lesson. It's much more systematic. You have 100 centimeters in one meter. You also have 100 centimeters in one liter. So it's much more systematic. There are standard SI units, and the standard SI units that you're going to need to know mainly for this class in this lab are the units for mass, the units for volume, and the units for length. So the standard measurement for mass is the gram, the standard for volume is the liter, and the standard for length is the meter. Grams are abbreviated with a lowercase g, liter is abbreviated with a capital L, and meter is abbreviated with a lowercase m.