Door-2-Math Blog

During the drop off today, I challenged Alexa to do a 3-digit number divided by a 1-digit.

“But I need paper for THAT”, she declared as all of my students do when they are first challenged for such task.

“Let’s try without one.  You’d be surprised how big of mental paper you have in your mind.”

“I do?”

“We all do.  Some of us use it more often than others and the ones use it more often have a bigger piece of ‘mental paper’.”

“Okay, let’s try one.”

“90 divide by 3”

“Oh, but I can’t do it without paper!”

“Let’s just try it!”

“Okay,” she hesitantly started.  “90 is inside the house, 3 says ‘knock, knock’ and 9 says ‘I can give you 3’ and 3 asked, ‘why 3?’” from there, she quickly realized that the answer is 3-0.

“Great job!  You mental paper just double in size!  Wanna try another one?”

“Sure!”

“123 divide by 3”

“Oh, that’s too hard!”

“Just give it a try, you’d be surprised at how powerful your mind is.”

“ 123 is inside the house, and 3 is out.  3 says ‘knock, knock’, and 1 inside the house says “uh, I don’t have enough to cover 3, so I’m going to bring a friend down.” Now it’s 12, so 12 says, ‘I can give you 4’.”  From there she got it that answer is 4-1.

Sensing that she still had room for more, I asked her “ what about 513 divided by 3”

“Would there be a remainder?”

“That’s a great question, Alexa!  The answer is no, no remainder and I’ll share you the secret after you get the answer.”

“Okay, so 3 says ‘knock, knock’ and 5 says, ‘I can give you 1’, and with 5 minus 3 is 2 and bring down a friend, so 21 says “I can give you 7’.  So it’s 1-7-1’

“Great!”

 So how did you know that there wouldn’t be any remainder?”

“The trick is that if you add all the digit together, if the sum is a multiple of 3, then you won’t have a remainder.”

“So, with 5-1-3, I have 6 plus 3 which is 9.  I see!”  (Good thing that she could see the big grin I had on my face or she’d be embarrassed!)

“Where do you get all those tricks?”

“Moms are special, aren’t they?”

By then, we got to the school, and she disappeared into her classroom as if I were never there in the first place.  Well, I’m back to be the chuffer as all the other chuffers signing in for their kids — just another day, another joy of motherhood.

Happy Zen Math!!

(c) Feenix Pan, 2007.  All rights reserved.

 While dropping off my children today, Alexa asked what a reminder is when it comes to division.

“  All remainder says is how much is left”.

“That’s it?”

“Yep.”  (when answering her questions about math, I pay particular attention to keep the answers as short as possible.  I pretend that I too am an 8-year old and am just having a conversion with her like her friends).

“Hm…, can we try one?” (Note: here, I waited for her initiation to try new things.  If she hadn’t prompted herself, at most, I’d ask one follow up question such as, wanna try one?  If the answer comes back negative, I move on to something else.  Hey, after all, we are adults, and we know a lot more to share than math, right?)

“91 divided by 9”

After some thoughts, she said, “ left over is 1”.

“wanna know a quicker way to say it?”

‘sure’, now she is all pumped up!

“we say it like a pro: ‘10R1’ – as in the answer is 10 with 1 as left over or we call it ‘remainder’”

“Cool!”

 Happy Zen Math!

(c) Feenix Pan, 2007.  All rights reserved.

During today’s drop off, I tested Byron and saw that he could add 9’s and 8’s pretty well (by taking 1 and 2 away and add ‘teen’ to what’s left over).  I then asked Bryon if he was ready to add 7’s.

“Sure!”

“Well, all adding 7 is about is take 3 away to your tummy and add ‘teen’ to what’s left over!  Wanna try one?”

“Okay.”

“What’s 7 plus 4?”

“two-teen” he promptly reported.

“hm…, close.  If you stick 4 fingers out and take 3 to your tummy for the 7 that’s already there, what do you have then?”  (Note:  I do my best to avoid the word ‘wrong’.  It sends the unwelcoming message to a young child that he is not getting it.  You don’t have use the word ‘close’ if you can find something else that says, ‘you are almost there, but not quite.  Give it another try.’)

“so, here is 4 fingers, and 3 go to my tummy…..1-teen!”

‘Great!  And 1-teen is…..”

“Eleven, of course!”

We then practiced a couple more.  Sensing his excitement for his school, as we got closer, I switched to who is doing what at school and with whom.  (Oh, boy, does he like to talk about his school!)

Happy Zen Math!!

(c) Feenix Pan, 2007.  All rights reserved.