Welcome to making a dichotomous key part one where we will make the flow diagram, which is needed to make the final dichotomous diagram, which will be in part two. Here are some almost random organisms, including my son, arranged in alphabetical order. Our job is to arrange these in a way that a total stranger who doesn't know what any of them are can identify them. That is the purpose of a dichotomous key. We need to think of a physical feature that will neatly and clearly separate these organisms into smaller groups. Something that applies all the time, something that is not subjective or is unsubjective as is possible. I am going to choose does it have legs? Clear, easy to understand. And then I'm going to organize these organisms to two groups. At this point it doesn't really matter. The things without legs and the things that do have legs. Just two piles not too important right now where they are. We can add in descriptors in this case this side will say no, this side will say yes. Looking at the organisms with no legs, I now have to find another physical feature that I can clearly and easily use to separate these. In this case does it have eyes? Add two lines and we have the first side done. Now looking at the organisms on the other side, we notice that two of them walk around on two legs, two of them walk around on more than two legs. So this is the physical feature that I will use to separate these organisms. We can quickly move these around to be in a group with two legs and more than two legs. And finally we have defined physical features to separate this group and this group which I have done as follows. And here we have our completed dichotomous key. No legs, no eyes, it's a carrot. No legs eyes, it's a snake, et cetera for all the organisms. This will work fine for these organisms. It probably will not work if other organisms are added because they will confuse the issue. But if we know our organisms, it works well. In part two, I'll show you how to convert this into the dichotomous key that we all tend to use when we're in the field.