 This session deals with measurement, or measurements. It is one of the several sessions that we have in the unit on basic laboratory math. And so measurement is what it's basically measures of basically counting something, determining how much of something you have or say even what temperature it is. And so that each characteristic, be it weight or volume, will have some unit. And you have familiarity with that. If I asked you to bring me a pound of flour, then you'd have a notion of what that means. Or if I said, oh, let's get a gallon of lemonade, we'd know what that meant. So in terms of the flour, the unit that I used was the pound, right? Or a pound. Whereas with the lemonade, I said we had a gallon. So in fact, those were our units. A unit is a unit is a precisely defined amount of some property. So we have an idea of what the definition of, of what a pound of flour looks like, or what a gallon of lemonade looks like. And a group of units taken together as in pound and gallon and foot or inch or whatnot, those that are units are together, comprise a measurement system. So we're going to say a measurement system is a group. And the measurement system that we're probably most familiar with in our everyday life is what we call the USCS system. Or the United States customary system. And that's actually a pretty good name for it, right? It's our United States. So a number of the measures within the United States customary system, the United States is the only place that would have that same measure, right? And it's customary because it's what across time folks in this country have agreed upon, right, as to what a pound was and what a gallon was, right? What each unit represents. Now one problem in the laboratory with the United States customary system that makes it cumbersome in the laboratory is that it's not systematic, right? And for instance, in measurements we have tablespoons and teaspoons and ounces and cups. And there's no consistent way. And we have two pints in a quart, four quarts in a gallon, even if there's 126 quarts in a barrel, right? So a barrel is a unit in the United States customary system. And we're used to those, we're used to working with them, but in the laboratory this lack of systematic relationship is problematic. So in the lab, right, in the lab, right, we're going to use the metric. And I know for some people if you're born and raised and comfortable with the United States customary system, it's a bit of a process to come to grips with the metric system and use it. But it is basically the language of the lab and you're going to have to embrace it. It's a bit like learning to tie your shoes. If you don't learn to tie your shoes, you can probably still walk around, but you're going to wind up stumbling a good bit. It's also a bit analogous to kind of learning a foreign language. Once you become fluent in it, then you don't worry about translating, right? Once you learn, if you go to France, people are speaking French, you're not going to worry about translating it back into English, or you're going to understand what they're saying, you're going to understand the signs, the menus in the restaurant, that kind of, you know. So once you're fluent in it, and that's what you're, so that's the point. We're going to have to learn the metric system and become fluent in it, if you will. Now initially, you know, to kind of learn relatively what the units are in the metric system, we're going to do some comparison with the U.S. customary system, and we're going to learn to do conversions, and we're going to do some mathematical conversion so that you learn how to do that. There are actually conversion applications for your smartphones that will convert it. But the point is, there's, you know, I won't say zero, but it's almost zero use in the laboratory once you learn the metric system. Everything's operating in the metric system. Your instructions are given in metrics. Your instruments are measuring in metrics. Your balances are weighing in grams. Your water baths are in degree centigrade. And your rulers are in millimeters and centimeters. So your instruments are working in metrics. Your instructions are working in metrics. And once your brain works in metrics, then you're set to go. Now, just as the United States customary system had its terminology, or USCS, the metric system falls under a measurement system. The measurement system that the metrics fall under is called SI for System International Units. You can tell I don't normally speak French, but we just call it the SI system. And so for just the international system of units. So we'll put that in English. And within that system, there are units and measurements for a lot of things, length, mass, time, temperature, and electrical current, you know, a number of different things. The units that we're going to be in this session, we're going to be worried about our length, weight, or mass. And volume, right? And we said that, you know, one of the key beauties, if you will, of the SI system or the metric system, is that it's systematic. It works in a systematic way. So you don't have to always start thinking, well, there are two teaspoons in a table spoon, or there are three, and what's a half a teaspoon? That type of thing. There's a basic unit for each of these measures. For the length, the basic unit is going to be the meter, right? For the weight, the basic unit is going to be the gram, and for the volume, the basic unit is going to be the liter. Then once we have that basic unit, then we're going to add either prefixes or suffixes to that basic unit to modify it, to quantify it within different amounts that we want to work with. So let's look at this table that has metric prefixes in everyday use and how the prefix is used with the standard unit to modify it. And let's use, for example, we'll work on volume. So what do we say our standard unit, the liter, right? So liter, sorry about that. So let's say we took this, so working with our table here on the metric prefixes and using the volume here, we said that for volume, the standard unit being the liter, right? So if that's a standard unit, and here the standard unit is here where it says none, there's no prefix or suffix, so it would just be the standard unit. So we had one liter, right? That would be it. Now let's talk about then, let's say one kilo liter. So here we have kilo as our prefix. Prefix for four liter means 1,000. So for one kilo, it is 1,000 liters. If we go to the next one, mega, right? Which is, what, 1 million. So 1 mega liter would be 1 million liters. Or let's put that in a notation or exponential form that would be 10 to the 6 liters. So we've got kilo, mega, gigatera. So you're probably familiar with these terms. If you're doing computers, this is how much storage space my computer has. Or this is how large a disk is. My flash drive has so many gigabytes. And that unit of measurement in the computer storage is bytes. How many terabyte hard drive do I have? The computer technology tends to be working up here in this range of gigatera. In the laboratory, we'll have kilograms and kilo liters. But most of our functions are going to be more down in the lower end of this. So let's look here at this one, milli. And if we put it in front of a liter, right? And here we say it 0.001. So that would be 0.001 liter or 10 to the minus 3 liters. Micro liter, right? Micro would be 10 to the minus 6 liters. So if we're working down, let's work you down. Let's do nano since it's on here. So notice what we've picked here on this table, particularly on what we've done milli, micro, and nano. We've done 3-fold, 3, 10-fold, 1,000-fold is what I'm talking about. 1,000-fold differences. So we have a liter. 1,000 of a liter is a milliliter. 1,000 of a milliliter is a microliter. And 1,000 of a microliter is a nanoliter. Now they all refer back here relative to the basic unit of a liter, right? So we have the 10 to the minus 3, minus 6, minus 9. But the ones that we've selected here are all 1,000-fold less than the previous one. So in terms of... So in these prefixes, I've selected liter, but we could do the same thing with gram as our unit. So we could have a milli-gram, a micro-gram, a nano. And we could do the same thing with the units of measure, meter. Millimeter, micrometer, nanometer. So it's very functional, very systematic. You have your basic unit of measurement, be it gram, liter, or meter. And then you have the appropriate prefix to add to the unit to define your value.