Tuesday, September 13, 2016

When Your Good Friends Don't (But Should) Get Along

I swear I'd give CalcDave's left arm (you're right handed, right Dave?) in order to be able to embed a GeoGebra applet into a Desmos activity.  I mentioned it, once or seven times, but that's right about the time the Desmos customer service director seems to drive into a tunnel.

I mean, I don't hate this activity or anything.

But I hate this slide.

Wednesday, September 7, 2016

Stupid Math Notation

Sometimes students show a misconception that makes me pause and wonder how we can continue without clearing this up.

Sometimes the misconception isn't their fault.

Take the "-" symbol for instance.  Are we talking about subtraction?  Negative numbers?  How about "the opposite"?  Or inverse; maybe it's inverse.

I gave students this number line today with the prompts.

1.  Tell me everything you can about the number P.
2.  Show where -P is on the number line. Tell me everything you know for sure about -P.

They did very will with the first prompt.  Lots of responses like:

"P is on the negative side."
"P is a negative number.  It's between -2 and -3."
"P is probably about -2.7 because it's closer to -3 than it is to -2."

Ok, I'm loving this.  Then they drop the hammer on me.

"-P is negative."
"-P is also on the negative side."
"-P has a negative sign in front of it so it's also negative."
What are your first steps when you encounter thing like this?  

Friday, September 2, 2016

The (Selfish) Reason I Keep Teaching

Pick a teacher's blog.  Go ahead, pick one.  Go through the archives and you'll likely find a post talking about vocation or calling or some other noble reason to enter the profession.  You'll also find some variation of the phrase "I don't teach subjects; I teach children." These are all true, but I don't think they get at why I teach.  I mean, I'm no Mr. Shoop and, while, I do think there's  satisfaction to be found in helping others, I'm not quite ready to side with the Tribbianian philosophy of good deeds. What I am willing to admit is that one of the things that keeps me teaching is a little selfish.

Let me explain.  When I was in high school, I took one of those aptitude tests.  The results of that test told me I should either be a teacher, a  youth pastor or, yes you guessed it, a cab driver.  At first, I was thinking, "Cab driver?  What's that about?"  But as I thought about it, these three career paths have something in common:  people.  So, then why teaching?  I'm going to try to impact people no matter what I do.  So why teach?

That brings me to the selfish reason:  Teaching is a case study in why people do what they do.  I'm really interested in that.

Dan recently asked about the motivation for moving away from the text book when lesson planning. I think this gets at why I'd rather do my own thing even though I didn't realize it when I first responded.  I want to know why kids do what they do, and most textbooks can only expose what they do.  If I make my own activity, I can ask the questions the way only I ask them. It's my way of starting the conversation with my students.

Today was a great example of this.  We were working through a Desmos activity where kids had to model sums using a number line.  (I really wanted them to be able to sketch on an interactive graph, but, whatever, can't have everything.)  But this activity exposed two really important misconceptions. One I was very aware of and the other I had never considered.

Misconception #1

I've seen this one before.  Often times students count the numbers and not the spaces.  Ok, got it.  I know how to deal with this. 

Misconception #2

At first glance I thought I had this one pegged too.  Students are just stating the length of the segment.  Through the discussion, however,  it came out that a significant number of students said the blue segment represented positive three because it was on the positive side of the number line.  

In 20 years, I've never seen that.  

It led to a nice chat about direction and location and how these can influence the value of a number.  

I don't have this conversation locked down.  And that's why I want to come to work on Tuesday. 

That and I want to see if Desmos has those sketchable interactive graphs yet.  

Monday, August 29, 2016

Math Don't Break

Integer operations are always an interesting endeavor with 7th grade students because they come pre-loaded with so many rules.  So. Many. Rules.

We've been talking about making our own rules, so we have this sequence of products and I ask students to discuss what patterns they notice.

-3 (3) = -9
-3 (2) =  -6
-3 (1) = -3
-3 (0) =  0
-3 (-1) = ??

Stuff we noticed:

"It starts with a -3 every time."
"It goes down by 1."
"It changes by 3."

I zero in to the apparent contradiction in going down by 1 and changing by 3 so we can clean up the language a bit.  This starts an nice little exchange about whether or not going from -9 to -6 is an increase or decrease.  We conclude it's actually an increase.  I have to remember to take my time here because this isn't an insignificant point:  Kids seem to think in absolute value.  

So what comes next? 

I wrote down everything I heard.  

"3".  "-3".  "4".  "-4".  

"Wow!"  I say.  "We've got a great argument about to happen.  This is awesome!  So many different opinions.  So which is it?"

Some minds change when groups start to discuss.  The students who thought 4 or -4 were thinking of sums and not products.  That leaves 3 or -3.  

"Ok, so which is it?"

If I had a dollar for every time a student said "A negative times a negative is a positive" followed by "because my teacher told me", I'd have all the dollars.  

But then Isaac offers a reason worth looking at. 

"I think it's -3, because positive 3 times positive 1 is positive 3, so negative 3 times negative 1 is negative 3."

So I write the following on the board:

(pos) (pos) = pos
(neg) (neg) = neg

We talk about this pattern Isaac. has noticed.  "Does this work for you all?"

Jordan speaks up, "I don't think so.  It has to be positive three so that it doesn't break the pattern."

"Which pattern is that?"

"The pattern goes from -9 to -6 to -3 to 0.  It's increasing by 3 each time so the next answer has to be 3."

"Why would that be so?" I ask. 

Then Vanessa chimes in.

 "Because math don't break."  

Thursday, August 25, 2016

Strategy vs. Procedure

I really want to focus on students being mindful of their process.  What they are doing is important, but they really need to know why they're doing it.  We've been doing daily exercises, How Many Squares?  that are based on Michael Fenton's activity, How Many Peaches?

We usually highlight different student strategies and have spent some time developing a continuum of strategies that looks something like:

counting --> grouping/adding --> skip counting --> multiplying --> writing/evaluating math expressions

This student's particular strategy generated a nice conversation.

I asked whether or not students thought this was a strong strategy.  Responses were less than enthusiastic so it was time to move a little.

Me:  Alright, if you think this is a strong strategy stand on this side of the room;  if you think it's not move to the other.

It was 31-2 in favor of the strong.  So I walk over to the "not strong" side and make my case.

Me: It can't be a strong strategy because the answer is 84 and this student said it was 76.

About half the class moves to my side.  I figure it was an even split on who was convinced by the "right answer" argument and who was convinced by the "I'm your teacher" argument.

Two students on the strong side raise their hands.

Student 1:  I think it's still a strong strategy because he probably just made a mistake.

Me:  Probably?  Where does that fall on our argument continuum, gut level, some reason or convincing reason?

Student 1:  Some reason.

Me:  Ok, great.  Can anyone take it to the next level?

Student 2:  I think it's still a strong strategy because he just counted 11 instead of 12 across the top.  He still multiplied right, but he just used the wrong numbers.  Everything else was good.

Yeah, that'll play.

Monday, August 22, 2016

From the Gut to the Head

Keeping in mind that we often get what we measure, I started from day 1 talking to students about an argument continuum.

Gut Level Answer

We're all pretty good at this one.  Offer an answer, but when asked why we .   This is often a student's default, especially if they're used to an answer getting culture.  

Answer With Some Reason

This is a step above the shrug, but isn't entirely satisfying.  I'm ok with students being in this area for a bit--"I think because " even if isn't completely convincing.  

Answer With Convincing Reason

I'm not really pleased with the wording on this one, but the gist is that we are looking for a student's thinking to be able to stand the test of peer review.  Does it convince others?  Can others use your process and arrive at the same conclusion?  If so, then we'll call this good.

I think this is something that I've had in my mind for as long as I've been teaching, but being more explicit about it with students has been beneficial.  I hear things like "show your work"  which has morphed into "show your thinking"  and I think they both are trying to get at the same thing.  Unfortunately, I think students usually interpret these in a quantitative way that amounts to something to check off the list.  Did I write a number of things down because teacher asked me to?  Yep, so let's move on.

As students begin to look at the quality of their work, we all win.

Wednesday, August 17, 2016

Don't Call it a Comeback...

...I haven't been here in (what seems like) years.

The past couple of years have been a whirlwind of change.  Full time math to full time elective to elective/part time math coach and now finally...

One section Math 7, three sections of electives and afternoon math coach.

Oh, and five of my 17 kids are now 17, 14, 11, 9 and 6 years old.  The older two are a senior and freshman (respectively) in high school while the younger three are still reaping the benefits of having an amazing mother who is willing to donate herself to homeschool.

It seems like a lot has changed since this blog was more active, but I hope to catch up with you all.