A great way that you can check, or make your own indicator, is making it out of red cabbage. Obviously, you find this in your vegetable grocery department, and it's quite interesting. What you do, is you go ahead and you take the cabbage, and you cut it in half. I've already done that here. Next thing you do, is you cut it into fourths. Take a sharp knife, and again, if you're a kid watching this, make sure you do this with the use of your parents. Go ahead, and you just cut it into fourths, just like this. There you have it. What you do, is you take a pot. You fill it with water, and you fill it about half way. You put your cabbage in here. You let it boil for fifteen to twenty minutes, and what you do, what comes out of there, is a juice that looks like this, and this is how you can check. When we combine this cabbage juice, in our everyday household items, we can check by the discoloration of it. What color it turns, to check to see how much acid, that each of these holds, so that's what we're going to actually try to do, so again, look at this juice, but after you boil this, in this pot, you kind of discard the cabbage, because you can't really use it again, but what you definitely want, is a juice, and you make sure you cool it down, but now if you're going to make your juice first, you want to make sure that if you're going to keep it out for more than two days, that you refrigerate it, and this is what we've done here. We've gone ahead, and made it ahead of time, so put this cabbage away, and that's what we're going to do.