## Wednesday, January 16, 2013

### Multiplication is Cool! (Or so my students told me!)

In my books, it's a pretty stellar day when your kids talk about the cool multiplication lesson they did ALL day - even at the end of the day walking out of school.

A few of my kiddos are still really struggling with multiplication - stemming from the fact that they have yet to memorize their math facts.  They understand the algorithm ... it's just the knowledge of the facts that are holding them back ... and I'm doing everything I can to help them get there (wish I could go home with a few of them to make sure they are practising at home, too).  Anyhow ... I digress ... sigh ...

I stumbled across a neat picture on pinterest this weekend.  It wasn't linked back to a blog that I can credit - just a website full of random pictures.  I was intrigued, though, and knew right away it was something I was going to try with my students.

This is it ... don't worry - it's not as confusing as it first looks.  I colour coded the example so you can see what we did.  You start with vertical lines - the three green lines on top represent the 3 tens in 32, the two red lines below show the two ones.  Then you do horizontal lines - two brown lines for the 2 tens in 25, and 5 blue lines for the 5 ones.

Going diagonally, you group where the lines intersect.  The group in the top left, then the middle groups, then the bottom right - since there are three groups of intersecting lines, there are three place value columns.  Count all the intersections in each group - in this case, there were 6 in the hundreds, 19 in the tens, and 10 in the ones.  We recorded the numbers in a place value chart.  After regrouping the place value columns, our answer showed 800 - the same answer we got when doing the standard algorithm.

How COOL!

I then asked students to pair up and create their own 2 digit by 2 digit multiplication question.  They had to solve it with the standard algorithm and the "plaid" picture.  They loved it!  And I LOVED the math talk that was happening.

Do you see those green dots in the corner of the pages?  I asked my students to code their papers with a traffic light comprehension dot - guess they were feeling pretty successful today - we were ALL green!  GO GREEN!

One of my pairs got so into it that they wanted to stay in at recess to keep exploring - they tried numbers with decimals and some 3-digit by 3-digit.  They didn't quite figure out the decimal numbers, but they worked away at the 3-digit multiplication and solved it!    Talk about perseverance and initiative!
For homework tonight, I asked the students to "teach" their parents or an older sibling about this strategy.  I can't wait to hear the stories they'll share tomorrow!

Happy Wednesday!

Jen

1. aaaahhhh, I get it! This is so very cool. I can't wait to show my class! Have I mentioned how much I love your blog to you lately? :)

2. my guys are also seriously struggling with their facts. it's so frustrating because it is so instrumental to every other concept (ie, the equivalent fractions we are working on right now!), but I can't spend days on end teaching facts. I understand the push towards a conceptual understanding of multiplication and division, but sometimes I wish we were still in age of drilling kids on their facts until they know them. :/

3. This was really neat to see! I wondering if you could take it even a step further and reinforce the place value ... Instead of saying 6 in the hundreds for example..write 600. 19 tens would be plus 190 and then the 10 ones would actually be plus 10 to get your 800 in the first problem. It's like reinforcing the idea of the actual place value when you multiply the 2x3..(20x30) instead of just the h column with the 6.
Thank you for sharing!!!
Michele

4. WOW! Can't wait to show this to my students.

5. Thank you for the explanation. I saw the picture on Pinterest earlier this week as well, but it just didn't make sense. Of course, I was exhausted when I saw it, so that probably didn't help. Your explanation makes it so clear!

6. Alright...this is a 4 star post!!! CLEVER idea with great rewards!!!! Kuddos to you...a must share!

7. I've seen this, too and can't wait to show my students when we start more complicated multiplication in a few weeks. You make it look easy, so now I'm willing to try it even more than before!

8. How cool! I've never seen multiplication taught that way before! And..I love the "comprehension dots!" What a great way to get a quick assessment of how well they are understanding! Genius!

Rachael :)
The Classroom Game Nook Blog

9. Hi Jen!

I can't wait to dig into the plaid idea!! You might be interested in a FREE site called Xtra Math that I've been using with my class all year... it is a quick daily drill of basic facts ( + - x and /) that you can program, and it tracks everything for you! My kids love it, and I've really seen progress!!

Erin :)

10. Read a post on this ... this is the way students in Japan are taught to multiply. There are many you tube videos on it. My husband and I experimented with it but I was fearful to show it to my kiddos because I could not get it to work with numbers that included a zero. I haven't tried your way with the colors though, that might help. Could you get it to work with zeros? Any advice to squish my fears of teaching the kiddos a more paper/time consuming way of multiplication? Thanks for the post!!!

11. It's so awesome that you're talking about this because I just watched an awesome YouTube video showing this method and bookmarked it for future reference.

Mrs. D

12. Wow this is soooo cool. I cannot wait to try this with my students when we finish practicing the "regular" method for figuring out 2-digit by 2-digit numbers:) Thanks for sharing this method!
Terri

13. I will try with my class and share with my wife!
Thanks!

Best,
Ramon
Fonts 4 Teachers
Fonts 4 Teachers in TPT

14. Amazingly cool! The kids will really find this fascinating!

15. Love this! Do you think it would work with decimal numbers?

16. I love this but you mixed up your vertical and horizontal lines!
You started with horizontal but called them vertical. Does it matter which you draw first?

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