 The next set of dilutions that you will be required to do in the lab is a serial dilution. So in a serial dilution, all the solutions that you make up have the same dilution factor. Now that is different from a dilution series where in a dilution series, the different dilutions that you make up have different dilution factors. So that is something important to bear in mind. Now I am going to show as an example, I'm going to make up a series of one in three dilutions. So that means when I'm finished making, I'm doing my serial dilution, all my test tubes except for the first one which has the stock solution is going to have a dilution, each of these test tubes will have a dilution factor of three since we're doing one in three serial dilutions. So the first thing of course to do is to add water to your test tubes. Here I added two mils of water to each of the test tubes and then the idea here is that first I'm going to take a mil of my stock solution, mix it into two mils of the first test tube, then I transfer, I take out a mil and put it into the next test tube I mix and I do the same thing, taking a mil from the last test tube, putting it into this one and I continue doing this until I have done one in three dilutions in every single step. So that is how you would do a one in three or a three fold serial dilution. So this is how I will do this. So I already have my water in my test tubes, so the only thing I need now is to add my one mil of stock dye, this is blue dye and I'm going to make sure I mix it by piping up and down so I mix it thoroughly and I'm going to transfer the solution I made, one mil of the solution, into the next test tube contained water. Again I mix thoroughly and then again I'm going to take one mil of this solution, add it to two mils of water in the next test tube so as you notice as I continue my stock dye is becoming more and more diluted and I will continue this process of serial dilution until I get to the last test tube. So in order to keep all the volumes equal I will just discard one mil of my last solution and then when you look at all of them, when you compare all the solutions together you will notice from left to right, trying to hold all of them together, that the solution gets, the dye solid gets less concentrated this is the stock dye and this is the most concentrated dye. So each of these solutions has a dilution factor of three, if you wanted to determine the final dilution factor of this last solution you would have to multiply three by three by three by three, so you will multiply in three by itself five times and that would give you the final dilution factor of this solution. So making serial dilutions are important, for example, in medicine when they want to determine a correct amount of dose of a medication to give to a patient, if you're not sure exactly of the dose that will work for a patient, you can do a series of dilutions to determine what dose is best suited that will probably manage the patients' complaints or the patient's illness. So that is how basically you do dilutions in the lab.