Today, we began our unit on subtraction. It seems weird to even say that, as I (still) feel that 3rd graders should know how to subtract BEFORE entering 3rd grade. However, at my school, they often don't, and even when they know the basics, they don't regroup (borrow) correctly. Or in some cases, at all.

The kids often just invert things in their minds. If the ones place says 2-7, they turn it around and compute 7-2. If it says 0-4, well that's easy, it's 4. After all, 4-0 is 4.

But things went pretty well today, when I shared a rhyme with them that I heard at my session on Friday. This is a rhyme that I'm sure has been around forever, but for whatever reason, I had never heard it before. Last year, I had success with my own made-up, "Tiny Top vs Big Bottom," but that hasn't seemed to stick this year. However, the kids really liked the new rhyme.

If there's more on the top -- No need to stop.

If there's more on the floor -- Let's go next door -- and get ten more.

If the numbers are the same -- Then zero is the name.

The kids loved it when I said that. Now getting THEM to say it proved a bit challenging in some cases. When they would tell me I needed to regroup on a problem, and I asked why, some of them shouted, "The top is smaller!!" When I tried to get them to recite the rhyme to me, I heard a few mishmashes including, "If there's more on the bottom, let's go next door. And get another ten."

OK, so in the ELA block, we'll work on what makes a rhyme.

Still, once we got into it, things went pretty well. Hopefully, this will help the procedure stick for when we're not just focused on subtraction.

I got a new kid in my class last week who really can't read, and I'm still a little iffy on his math skills. The first day he was with me, we took a test, and looking at his answers made me really question his methods.

The thing is, it's true when they say that there are multiple correct methods to get to the correct answer. I just don't think I had ever seen the method that this kid utilizes. He apparently does a math problem the same way Billy from Family Circus runs all over the neighborhood, following that convoluted dashed line.

An example problem:

The test was mostly over simple subtraction. One of the questions was 99-69. The good thing is that this boy shows his work on his paper, so I was able to CSI it and do a little forensic math investigation to track back how he solved the problem. As near as I can tell, here is how he solved 99-69:

First, he stacked the numbers up, as he should:
99
-69
----

Next, he looked at the Ones place, saw 9-9 and decided to regroup (or borrow). So he crossed off the 9 in the Tens place and made it an 8. Then he crossed off the 9 in the Ones place and made it a 19.

He subtracted 19 - 9 and got 10. So he put the 0 in the Ones place of the answer space and regrouped again (carrying the one this time). Now, he had an 8 AND a 1 up above the Tens place, so he added them and got 9. He then subtracted 9 - 6 and got 3, which he put in the Tens place.

Voila, his answer was 30, the correct answer.

Oh, and did I mention little "sticks" were everywhere, enabling him to do the actual subtraction and adding of each step?

I think if I give this kid 9 hours for each test, he will do OK...