Briefly, from the wikipedia link,
Titration is a common laboratory method of quantitative/chemical analysis that can be used to determine the concentration of a known reactant. {click} . You use an indicator, or a selective electrode to let you know when you've consumed all reactant, and a careful volume measurement to let you quantitate that reactant.
Your particular application cited on the web page you linked gives you some other hints, "Incubate tubes containing Catalase and Hydrogen Peroxide at different temperatures and examine the rate of Enzyme actvivty by titrating any remaining (unreacted) substrate. This will give us an indirect measure of the substrate converted to product and therefore the rate of the reaction. (remaining substrate = Starting amount - amount converted to product)." On how you're going to use titration to determine enzymatic reaction rates.
You can think of hydrogen peroxide as the substrate or reactant for either catalase (found in most animal tissue, liver in your case) or permanganate. We just use the words "substrate" and "reactant" respectively, in each case, by convention. (I realize that an enzyme is a catalyst and not a synonym for reactant, I'm just running with the comsumption of the substrate theme here)
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And, damn, but your class is really up on the teaching tech isn't it. That is one elaborate flash animation. Back in my day, oh, these old bones, we only had a lab book to follow. Didn't you go through it? It is really very informative, stepwise. Or did you write it? Top marks, to whoever wrote it. 'Tho they might have bothered to run it through a spell checker.
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Hey, I got all the questions right. Do I win anything?