Saturday, June 25, 2011

Multiplication --Part 1

Let, me start by saying that I believe that everyone should know their multiplication facts by heart.

I often have sixth grade students tell me they hate Math.  After many years, I have learned that usually means I don't know my basic facts:  addition, subtraction, multiplication, and division.

Through a series of posts I hope to share with you, some of my observations and things I do to help them all learn with short cuts, games, testing, etc.  I hope you join in by sharing your tips, etc.

Since fractions are a huge part of the sixth grade math curriculum, I know that multiplication and division have to be a big push fast.  I also know that normally there is a huge sense of everyone knows this but me, and I will never be able to learn this.

To overcome the I can't learn this, I always start with the nines.  I usually start with two different ways to do the nines "secretly".  I only share one way with a student, to keep from overwhelming them.  Which one is based upon the individual student.

The first one I show them is with their hands.  It basically goes like this.

1.  Place your hands in the air with your palms facing you.

2.  How many fingers and thumbs do you see?  10

3.  The problem we are going to solve is 4 x 9  (Write on a piece of paper 4 x 9 = )

4.  What number are we multiplying times 9?  4

5.  Count over four digits on your left hand and bend that finger down.  (This would be the ring finger.)

6.  How many fingers are before that bent finger?  3  (Write down that digit for the student to see.  Now the paper shows 4 x 9 = 3)

7.  How many total fingers are following the finger that is bent?  6 (Write down that number following the 3.  Now the paper is saying 4 x 9 = 36)

8.  Ask the student to read you what is on the paper.  4 x 9 =36

 I then always say, That's right, I thought you told me you couldn't do multiplication.  I have literally had students sit and cry because they didn't think they would ever be able to get it.  Suddenly they have become experts at their 9's and you can immediately see that confidence returning.  They always want to do a lot of problems with 9's right then to be sure they really can do the work.

With students who are trying to "hide" the use of their hands I show them this method.  The conversation usually goes as follows.

1.  We are going to work the problem 7 x 9. (Write down 7 x 9 = ) The normal reply is I don't need to know this stupid stuff.  I told you I don't know and I don't care.

2.  That is okay but we are still going to work this problem together.  Can you tell me what number we are multiplying times 9?  You must think I am stupid, to ask me that.  It is a seven.

3.  Okay, what is 7 -1 ?  Six  (Write down the six.  Now it looks like this.  7 x 9 = 6 )

4.  Six plus what equals nine?  3  (Write down the three.  7 x 9 = 63)

5.  Read me what is written down. 

After reading what is written, you can usually see their whole attitude and body language change.  They usually say, "Let me do it this time.  Give me another problem!" 

I usually use the second method with students above the sixth grade, as they often do not want to have others see them using their hands.

Next post topic:  Numbers other than 9

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Teacher Mum

I love that you have posted about the first x9 strategy (I did not know the second one but will definitely use it now.) I totally agree with everything you said and I have had the exact same experiences with the kids getting excited about realisisng that they actually can do it. It sets them off to learn all the other times tables.
Thanks for sharing.

Workshop Classroom

I never knew the second method...thanks for sharing!!

Pam B

There is a great video on Teachertube about multiplying by 3, 6, and 9, and multipying by 7 using a tictactoe board. It is really cool and I think older kids could learn it. I tried with my third graders, but they could not get it.

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