 Okay, at this point we are going to go over some of the types of things that can be measured, that you are probably going to have to be involved in measuring in this class, and we're going to talk about the units that are used to measure them in the metric system. So the first one that we're going to talk about is length. As I mentioned earlier, is the distance between two points, so let's say the distance from here to here, or if you want to measure how tall a person is, maybe the distance from here to the top of their head, but basically any time you're measuring the distance between two points, you're measuring the length of something. And as I mentioned earlier, the metric system has a special unit for measuring length called the meter. Again, the abbreviation is a lowercase m, and there are metric variations on the meter that we will talk about in a little bit, but right now I just want to talk about what a meter is. Meter is about one single meter, the distance is about a little bit more than one yard long, so you may know what a yard is. Another way of thinking about how long a one meter is, is it's about the length, let's say from your shoulder to the tips of your fingers, if you stretched out your arm as far as it could go, roughly speaking, obviously everybody's a little bit different in size, but that's roughly what the length of one yard is. So we're going to talk about the variations on the meter in a little bit, but let's go on to the next slide. Okay, volume, as I mentioned earlier again, my informal definition of volume is how much space something takes up in three dimensions, or 3D. So the metric system for measuring volume is called the leader, and again I mentioned the abbreviations are lowercase or uppercase letter L. There are variations on that unit, there are variations on what a unit is that are related to the leader, we will talk about that again in a little bit. I figure most people are familiar with a 2-liter soda bottle, so what that means is this soda bottle contains soda, there's the soda, that takes up 2 liters worth of space in three dimensions. So maybe if you had half of the soda right there, that's about 1 liters worth of 3-dimensional space, but the 2-liter bottles, they contain twice as much, so 2 liters. This device over here, it's called a graduated cylinder, hopefully it makes sense why it's called a cylinder, because basically it's a tube, graduated just means that it has little markings where you can make readings on. And graduated cylinder is kind of a standard device that's used in labs to measure how much space liquids take up in three dimensions. So over here we've got some liquid, and the line that says 1000 here is actually equal to 1 liter. And whatever this purple liquid is, it's taking up a certain amount of space, and it's almost one liter's worth of space, or one liter's worth of volume, but it's not quite making it there, it's a 950, what's called a milliliter, but we'll talk about that in a minute. All I want you to realize is that volume, the metric system uses liters for measuring that unit, there will be variations on the leader unit that we'll talk about in a minute, but there you have it. And I guess graduated cylinders are sometimes used to measure the volume of things, especially liquids. Mass is something else that can be measured. As I mentioned earlier, we're cutting a corner, and as far as we are concerned, mass is roughly the same thing as weight, and I am going to use that interchangeably. Again, the metric system uses something called a gram as its unit for measuring mass. One of the informal definitions that gets used a lot for how much a gram is, one gram's worth of weight is about equal to the standard metallic paper clip. If you have a standard metallic paper clip, that usually weighs about one gram, or has a mass of about one gram. The typical thing that you use to measure mass is an electronic balance or an electronic scale. Here they are trying to measure the mass of this nickel, and you can see that the nickel has a mass of approximately 5.01, and if you focus in right where I'm circling, there's a little G there, which means that nickel weighs 5.01 grams. Or if you want to think about it this way, this nickel has the weight of about five paper clips, so keep that in mind. And then you can measure other things that weigh much less than a gram, and we'll talk about that in a minute. And so ignore this, ignore this for the moment, pretend it's not there. Let's see, temperature, we also talked about informal definition of temperature is how hot or cold certain things are. Again, the metric system uses a unit called degree Celsius for measuring temperature. The SI system uses something called a Kelvin, and it's abbreviated with a K, and no degree symbol. These are some temperatures that are, well, I hesitate to say they are important temperatures to remember, but they're important for this course, so I'd like you to know these. I'd like you to know the fact that water freezes at 32 degrees Fahrenheit. Another way of saying 32 degrees Fahrenheit is to use the Celsius unit and water freezes at zero degrees Celsius. So these two numbers are just two different ways of saying the same thing. The only reason the numbers are different is because we're using different units. And again, the same temperature in Kelvin is 273 Kelvin. That's, again, I'm cutting a tiny bit of a corner, I believe it's 273.15 Kelvin, but you don't need to know the .15. So you should know what temperature water freezes at in all three units. The easiest one to remember, or at least this is the propaganda that they sold me when I was in elementary school, is the metric system measurement for temperature, because it's easy to remember the number zero. Not so easy to remember the number 32, not so easy to remember the number 273, but eventually you will get to know them all. Water freezes, water also melts at 32 degrees Fahrenheit, or zero degrees Celsius, or 273 Kelvin. Those are all three different ways of saying the same thing. Everything between Celsius and Fahrenheit. So going from Celsius to Fahrenheit or Fahrenheit back to Celsius is a little bit complicated. I think we're going to talk about it in a little bit, but right now just ignore it. Converting from, let me erase some of this noise, converting from Celsius to Kelvin is really easy. You just take whatever the number is in Celsius and you add 273. So if the temperature is zero degrees Celsius and you want to know what the same temperature would be written in Kelvin units, you would just take zero and add 273. So zero degrees Celsius is the same as 273 Kelvin. The other three temperatures that I want you to memorize are the temperatures that water boils or water condenses at. So if you have steam and you want to turn it back into water, that means you're condensing the water. If you have water and you want to turn it into steam, that means you're boiling it away. The standard temperature that water boils at in degrees Fahrenheit is 212. The same temperature in the different unit of Celsius is 100 degrees Celsius. And again, when I was a kid, the nuns basically tried to tell me that Celsius and the metric system were the way to go because it's way easier to remember the number 100 than it is to remember the number 212. So if that helps you, 100 degrees Celsius is the standard temperature that water boils at or that water condenses at. And then finally, if you want to know what 100 degrees Celsius is in Kelvin, what did I say a minute ago? You add 273. So what's 100 plus 273? It's 373. So water boils at 373 Kelvin. Doesn't this guy look fun? All right, as far as summing up what you should know on the previous slides, you should know what the standard metric units and their abbreviations are for length, volume, mass, temperature, and time. And you should also know that the SI system uses a different unit called Kelvin as its unit for describing temperature or measuring temperature. So I'm coming back to the slide for a moment. One of the things that I want you to realize is that these are not the only units, meter, liter, gram, Celsius seconds. Those are not the only units that are part of the metric system. I said the metric system was a collection of units. It's just that these are the most common ones that are used a lot out there in the real world. So those are the ones that I want you to know. There are plenty of other features of material objects that you can measure that are not these, but we're really not going to cover them in this course. We might cover one or two as we go along, but I just want you to realize that there's more than what you're seeing at the moment.