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If you are a math person, you’ve probably heard about dear Aunt Sally. It is a mnemonic that helps students remember the order of operations (the order in which we work a series of numbers and operations). It is “Please Excuse My Dear Aunt Sally. Please is for parenthesis, Excuse for exponents, My for multiply, Dear for divide, Aunt for addition, and Sally for subtraction. Every math teacher I know uses it and if they don’t, then they probably should. I taught the students the mnemonic, worked several examples, had them work several examples, gave them a short worksheet, and then today we played a game. The game was a set of 40 pieces of paper cut up into about 2″ by 4″ or 5″. I wrote a different numeric expression on each paper. The students were in groups of three or four. Each group got a set of the cards and a dice. The whole set of cards was placed upside down in the middle of the group. The first person rolled the dice and flipped over a card. They worked the problem on the card while (at least) a second person worked the problem as well, as a “checker”. If the person got it correct, they added the number on the dice. If they got it incorrect, they deducted the number of points on the dice. It was absolutely hilarious to listen to the students argue and correct each other the whole time they played. There was very little off-task conversations. They occassionally asked for my help, but not often. It was a very successful game and lesson! It sometimes got very loud in the room, but what was I going to say, “Quit talking so loud about math!”? Uuummm… NO! I’m goint to post pictures of the cards I made up, but honestly I just got them out of the book.
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Hi,
Please take a look at this article:
http://blogs.edweek.org/teachers/coach_gs_teaching_tips/2011/01/math_teachers_please_excuse_dear_aunt_sally–forever.html
Take the expression “100/10*10/100″ for example.
People learning PEMDAS might try to multiply before dividing, resulting in the incorrect answer of .01. Multiplying and dividing are at the same level, and therefore you must evaluate from left to right.
100/10*10/100 = 10*10/100 = 100/100 = 1
The rule should be to evaluate inside the parens, then look for exponents, then multiple OR divide, then add OR subtract.
1) Parens
2) Exponents
3) Multiply/Divide
4) Add/Subtract
todd james recently posted..Standard Unit Conversion Packet
Enjoyed the article, but I still think that Aunt Sally is a wonderful tool. When I teach it, I most definitely make sure they know the “multiply and divide” are together and the “add and subtract” are together. We say “parenthesis, exponents, multiply or divide which ever comes first from left to right, then add or subtract whichever comes first from left to right.” The comments on the article were just as interesting as the article itself. I think it is extremely important to teach students understanding the concept, but students must also have fun things to help them remember about the concept as well. In my teaching, I’ve taught kids through hands on manipulatives and discovery for conceptual understanding but they will still forget. It’s important to have those hands-on, games, mnemonic devices to refer to when the students forget. Thank you for your comment and for referring me to the article.
Andrea Kerr recently posted..Standard Unit Conversion Packet