Thursday, January 5, 2012

Tricky Math

 Math is not my strong suit. I hated math in school and always challenged teachers to prove I would use it anywhere in real life. I never finished algebra because the teacher couldn't site a single time I would use it in the real world unless I went into drafting (which was obvious I had no interest in). So, I learned all kinds of techniques to help me with math so I didn't look like a complete dunce if I had to add something up on the fly. Like calculating if I had enough money while standing at the register with ten people staring at me. So, here are a few cool techniques and links I've used to help my kids learn their math.

Multiplication comes with various tricks, and teaching them to my kids is important because, I just memorized my times tables, so trying to explain why 9 x 8 = 72 gets tricky when you can't say, "Because it just does." It has to make sense. There is a cool hand counting technique that you have to try because it is so clever. It only works for the nines tables, but still neat. "Multiplication 9s Trick" is a pdf file that also has a worksheet attached so you can print it out for a lesson and then have your child use the technique to solve problems.

Another trick that I figured out as a kid, is that whatever the number is (1 - 10), subtract one from it. That tells you the first number in the answer. Then whatever you have to add to that number, to make nine is the second number. For example: 9 x 8  take 1 - 8 = 7 so that means seven is the first number. How many then do you have to add to seven to make nine? The answer is two. So the answer to nine times eight is seventy-two (7 + 2 = 9).

With subtraction and addition, I taught the kids that they can always check their work by working the problem backwards. So, 9 - 8 = 1 and reversed 1 + 8 = 9 . Likewise, 9 + 8 = 17 so in reverse, 17 - 8 = 9 . This has made it possible for the kids to check their own work before turning it in, and they are more likely to have more right answers.

About 45 minutes past cherry pie.
We haven't gotten to division yet, but I'm already searching for tricks to figuring those out. Teaching how to tell time was fun when we used the illustration of pie to figure out sections of time. Money also came into play, to explain quarters of an hour. Here is where I got the inspiration for using pie to illustrate time. It's a story with worksheets, called "15 Minutes of Pie". I also drew up on our dry erase board, a clock and labeled each hour with it's five minute increments, labeled the hour and minute hand, and then talked about half an hour being thirty minutes, or HALF the pie. The kids really took to it. Then they asked for cherry pie for lunch. Oh well. Food is a good motivator, that comes with risks.

I hope you found some inspiration. Good luck with those math lessons. Just think, if you struggle with math like I do, all this is strengthening your own knowledge and that's a good thing!

If you are interested in any more of the printable worksheets like the examples I provided. Check out Super Teacher Worksheets. A great site with really creative ideas and fun printables, all free. Update: The site Super Teacher Worksheets has become a paid membership site. There are some freebies, but not many. Bummer, but still an excellent site if you are able to pay for it.
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