ParenthesisDate: 03/09/99 at 09:26:18 From: Jeremy Ravenscraft Subject: Parenthesis I know how to do parentheses, but the problem is that I have to teach a class for the day, and I really have no idea how to explain how they work. Can you help me with that? Date: 03/09/99 at 12:54:12 From: Doctor Peterson Subject: Re: Parenthesis I have all sorts of ways to describe parentheses for people who have trouble grasping the concept. One good way is just to write an expression on the board and turn each pair of parentheses into a circle enclosing the parenthesized part completely. You will end up with something like this: ------------- / \ / \ | ----- | | / \ | 2 + ( ( 9 - 5 ) / 4 + 2 ) / 3 | \ / | | ----- | \ / \ / ------------- You have to turn the contents of each circle into a single number, then replace the whole circle with that number and continue. You can do this step by step, each time redrawing the expression with less stuff in it. You can make up a silly story about black holes collapsing or something, to make it fun. You might even want to start with just the circles (not parentheses), and after showing this, erase the top and bottom leaving just a little curve at each end of a circle - the parentheses! Other ways to talk about parentheses include "boxes within boxes," each box having to be opened in order; this is most useful if you are talking at the level of algebra, with some variables inside; you solve equations by "unwrapping" one box at a time (undoing the operations) until the variable inside is revealed. Or you can make diagrams like this: 2 + ( ( 9 - 5 ) / 4 + 2 ) / 3 \_____/ 4 \_________________/ 3 \___________________________/ 3 Since I am not sure of the level of your presentation, I have probably missed some of what you want to talk about; but this may give you some ideas of your own. - Doctor Peterson, The Math Forum http://mathforum.org/dr.math/ |
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