Friday, November 28, 2008

Laws of Sine & Cosine

We've recently worked through those laws in precalculus. This is my 5th year teaching them at this school, and I think I've finally settled on a way to present the "ambiguous ... A.S.S. case" for the Law of Sines.

This I've done before and this year: I present a sheet that has 3 situations drawn in which I have a partially made ASS case but ask them to use their rulers to complete the triangle with the last "S". For example, for triangle ABC. I've drawn a long line for the "base" of the triangle representing side b. I've measured and drawn in angle A of 31 degrees and side c of 5 cm. B is at the top of the triangle, and they're to draw segment BC of length 3 cm to complete the triangle. I eventually get them to see that there are 2 triangles they could draw. Then we see how this plays out without drawing and why there are 2 triangles mathematically.

I also do this for the cases where there is one and zero triangles.

In the past, I used to make a big case of how you could tell there was a 2nd triangle by looking at the given information and if the 2nd "S" in ASS info given is longer or shorter than the 1st "S" then you make some decisions. Hmmm, made sense to me, and that's how I still do it myself, but the students weren't always successful.

This year, I just said: after you solve for your 1st angle, try for the 2nd option of that same angle and "see if it works" (you can add up to 180). That seemed to work for more students.

We also just did Law of Cosines. I had everyone create their own scalene, non right triangles and measure all sides and angles. Then we plugged into the formula to see why it may work (instead of just proving it to them or just showing them the formula). I always hesitate with this measuring thing because the numbers never work out EXACTLY. But I figure, it's a good opportunity to discuss human error and measurement tools and degrees of accuracy and such. I make a game out of it and make my own triangle and ask if they can beat my "closeness". Depending on the class, I was off by anywhere from 0.3 to 1.5 units when the 2 sides should have been equal. I blamed my aging eyes (cough cough).

Sunday, November 23, 2008


Ackh! It's a few weeks until the students have to start thinking about and studying for (cough cough) finals. For the past couple of class periods in precalculus I haven't really gone over new material since they were getting ready for a test on graphing all the trigonometric functions. Instead of not assigning homework, I decided to assign OLD topics and grade on accuracy instead of just completion like I normally do.

The first assignment was on function notation, and the current one is on function composition. I gave them the stern teacher face of "don't show up and say you don't know how to do it. Look at your old notes and look at the book examples and look at the web, but LOOK and recall and do something for yourself." Gee. My face is expressive.

Anyway. I was giving the graphing test on Friday, and the homework was due, but I didn't collect it until after the test. Some students finished early and were doing various things. Two friends started to look suspicious. I saw one pass back a paper to the other. Then I saw the other surreptitiously copying her paper. Crap. I walked over and quietly said, "do not do that! That is a zero for both of you. Do your own work.". I was so mad. First for her doing it, and equally for thinking that I'm so oblivious, that I can't notice what's going on.

I debated talking to both after class (I didn't). I had the whole speech prepared in my head about how once you lose someone's trust, it's very hard to gain it back. But I settled for the unhappy glances their way and the ignoring of them and a total change of my demeanor towards them after the test was over, and we were going over other concepts. I'd had a hard enough week, and I didn't want to deal with more stress.

Tuesday, November 18, 2008

November Slump

Sheesh. I forget this happens every year. I get super depressed and down on various kid behavior and teaching and the stress and all the whole bundle every year at about this time. I think I should make a cross-stitch sampler to remind myself that this will pass, and things do get better SOON.

It's been especially bad this year. We are mandated from above to have meetings up the wazoo that suck the life out of our planning periods. Then we are dictated to teach to the "exit exam" in a specified way and eat into our regular curriculum to do this. Then .... then .... then.

I think I have enough seniority to say "phhhphflt" and do what I think is best for the students: a type of don't-ask-don't-tell policy. My rationalization is that if questioned, I'll have a valid reason for why I think what I'm doing is the best for my kids.

On a positive note. My students are mostly great. Highlights:

One shared with me her way of remembering the sine and cosine graphs. She's Hispanic, and "sin" in Spanish means "without", so that's the one that is zero at zero. And "con" in Spanish means "with", so that's the one that has a value at zero.

A day or so ago we were doing the ambiguous case of "Law of Sines", and for the "no triangle case". I wanted to show them that in the A.S.S. case when they're first solving for the angle, the ratio of sides is 1._____. So I asked what happened on their calculators when they tried to solve sin x = 1._____. They said, "ERROR". Then I said, okay, close your eyes and picture the graph of y = sin x. My goal was to get them to see that the largest it could be was 1. So I asked, after they were thinking for a while on what the graph looks like, "what do you see?". One kid answered, "ERROR".

Anyway. Some of us got together tonight as a math department and went out for a drink after work and destressed and laughed and such. That will go a long way to making the rest of the 6 weeks livable.

Sunday, November 16, 2008

The Power of Off-The-Cuff Words

Just recently, my memory was refreshed as to how seriously students take what we say. Things I just sort of blurt out because I think they're the right thing to say seem to make a difference.

For example, I have this incredibly smart and hard-working student in BC Calculus this year. Last year I had her for precalculus preAP. Back then she was talking about her math choices for the next year, and I mentioned that she should definitely take BC calculus as opposed to AB because she had such a great work ethic and cared about really understanding topics and such. I think I also said something to the effect that it would be a waste of her time to take AB which would not challenge her as much. I did truly believe this, but I didn't know how much weight this would carry. Well, several times this year as she's bemoaning the fact of how hard it is (in a good-natured I'll-still-muddle-through sort of way), she kept mentioning the fact that I made her take BC calculus. Hmph.

I have another student in AB Calculus. I also had him in precalculus preAP last year. He's an interesting, intense, strange, slow-working, self-stressing type of person. I really did not think he could manage the pace of calculus with how much he frets over EVERYTHING. He asked last year if he should take calculus, and I hate to discourage students/people, because, really, what do I know, maybe they will surprise themselves and me and if not, then the experience will be a learning one one way or another. So here he is in AB calculus this year. He is struggling and stressing and such all along. He came to me after school one day and said he wanted to drop out of the class. I said that well, the decision was his, but I think it would be a shame if he did because then if anything hard came up in the future then his first idea would be just to quit because it was too hard. I also said that he was smart enough to handle it, and personally I would stick it out. (inside, I think he can do it, and he just has to approach it in a different way, but I DEFINITELY know that if he dropped, he'd be WAY less stressed than he is now). Well, anyway, he decided to stay, and later wrote me a note thanking me for believing in him and in his ability.

I guess the point of all this is to err on the side of pushing the kids to do their best and to do things they don't think they could do or think possible. Maybe it will open up opportunities for them and make them think of themselves in ways they didn't in the past.

Saturday, November 08, 2008

Foreign Exchange Students

At my school we seem to get a lot of foreign exchange students. Every year I've had at least one; always from Germany; and last year I had 3. Phew! This year I again have 2 girls from Germany, and lo and behold one boy from China.

Well, a while into the school year, I saw that he wasn't interacting with the other students, and they weren't talking to them. I don't think it was a rudeness thing on either part. My sense is, that the girls (and boy) from Germany in the past and present were so cute and approachable and maybe "looked more like them", that they naturally talked to them and became friends. That's my guess, and now that I put it down in words, it seems kind of wrong somehow (the situation). Why hasn't anyone struck up a friendship with this boy? Maybe I'm just misreading the situation, and it's only in my class that this phenomenon occurs.

Just yesterday I asked the boy from China (He's cute: when he first arrived, he said, "My American name is Eric" ... I finally asked him his real name, and he mentioned it, and I've been practicing it, so now I use it when I talk with him). Anyway, I asked him to talk to the class about how school differs in China from our school. Sheesh. That was a cultural wake-up call for my kids.

He said they start school at 7am, and have 4 classes until 12pm. Then they have a 2 hour lunch break, and at 2pm until 7pm, they have 4 more classes. Then they have 2 hours of studying. They have a month off in the spring for a sports festival. Every year (?) they take off one week for each of the following activities (?) working in the factories, farms, and army. The sports they play are tennis, running, ping-pong, and badmington (for some reason, that got a titter from my students). I guess I was surprised there was no soccer.

Anyway, hopefully, he's getting a chance to interact with students and such and not having a lonely existence of a day.

Sunday, November 02, 2008

9th graders

I'm teaching one section of algebra 1 preAP this year, and I feel like I take extra care of them ... because they're "young uns", and they're learning the foundation for everything else that comes, and they're just so darned cute most of the times. With that said, there are still some "young uns" issues.

There's one whiney child that grates on my last nerve, and I have to work extra hard to not show it. Everything we do, her response is (insert whine), "I don't get it. I don't get anything." She needs to be hand-held through every step. It got to the point where she snapped back at me in class one day because I told her to get to work when she was chatting (because she JUST didn't get it and was waiting for me to do things as opposed to getting help from her more capable group mates).

I was super frustrated last week, so I sent e-mail to her other teachers to explain the situation and to see if it was just me and my class or if these issues came up elsewhere. Two other teachers responded and mimicked what I said about her neediness. They mentioned that she either has a capable friend sitting by her to help or the teacher literally DOES break things down into baby steps. This made me feel better and gave me an idea of copying extra "reteach" sheets for each topic so that she'll have extra practice to look at while the rest of the class is "zooming" along.

She was better in class this last time, but had to leave, so I didn't get to test out my extra-sheet idea yet.

I'm also dealing with a large portion of the class (4-6 out of 28) not turning in ANY homework. I think they're still used to middle school where you magically pass no matter what. I've made some calls home, so hopefully that will produce some late work this coming week.