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.

Back in the day, I used to be an avid comic book collector. Last week? No, I'm talking about when I was in high school. Instead of dating, I had my superhero stories. Worked out ok in the end.

Well, we gave a subtraction test this past Thursday, and MOST of my kids did pretty well. Which is a good thing, since we've been practicing subtraction pretty extensively for the past 2 weeks!!

The good news is that I started the year with about 4/5 of my kids thinking that 2-8=6 (not regrouping), and now I only have 4 or 5 kids that still do that on a regular basis. In fact, one of the questions on the test was "How do you know when you are supposed to regroup on a subtraction question?" I am pleased to say that all but about 3 of the kids answered something to the effect of "When you have a tiny top and a big bottom."

Of course, some of my kids who still don't regroup got that question correct, so they KNOW when they are supposed to regroup in theory, they just don't put it into practice...

What disappointed me was the other short answer question. Much like on our addition test, where I was looking for the word 'SUM,' I posed a similar question on this test:

What is the math word that means "the answer to a subtraction problem?"

The answer, of course, is "Difference." This is something that we have talked about repeatedly, used in word problems, and it was even up on the board on a Clue Word list. However, I only had 16 kids (out of 40) that got this question correct.

Wrong answers included the following:

Sum (I guess they missed it on the last test and hoped to jump on the bandwagon this time)

Check your work (Good advice, but does not answer the question)

How many more

Take away

Compare

Left (These words at least are subtraction clue words, but still don't answer my question)

Subtract (Too obvious, kid)

And my personal favorite (*SARCASM ALERT!!*):

Addition.

Yeah, the answer to a SUBTRACTION problem is called "The Addition."

Just when I thought we had mastered the concept of opposites...

Today was a really good day for math class. We had designated it as a Problem Solving day, so I had the kids work in groups to solve word problems. We've been going over subtraction for the past couple of weeks, so I had written up 5 subtraction word problems -- none of which used the word "left" -- and gave one to each group.

The groups then copied the problem onto a larger piece of posterboard and went through the steps of solving the problem.

For the most part, the kids worked well together, talked out the problems, and took their fair share of the work. We had made up a rubric for groupwork beforehand, and the kids graded themselves and their partners after they were done with the problem.

After that, though, the really enjoyable part began. I posted the problems on the walls around the room and had each group choose a "docent" -- a group member to stand by the poster and answer any questions or explain the process to the groups that would rotate around during the gallery walk.

Once the gallery walk began and groups were checking out each other's work, I walked around and listened in. I really enjoyed hearing discussions of which number in the problem was the "whole" and which were the "parts;" how "difference" means the same thing as "how many more;" how you are supposed to round numbers if the question has the word "about" in it; how there is no possible way 38 dogs still need to be fed if there were only 21 dogs to begin with and 17 of them have already been fed.

I still have some incredibly low kids in my class, there is no way around that. But I also have a large group of kids that are really beginning to show great thinking skills and the ability to share their reasoning.