BCA part two

Half way through the unit.  One thing we’ve noticed about BCA is that it is much easier to find the misconception that students have about what goes on in a reaction and correct it right away.

Lab on Monday.  I like to blend the old with the new and have, therefore, dusted off an oldie.  Mixing two solutions together to form a precipitate and filter.  From the mass of the precipitate, they have to find the Molarity of the original limiting reactant.

As this is my first time with BCA, every time a student comes in with a question, I’m making a note of what to change for next year.  the latest one is to remember to stress “subtract reactants” and “Add products”

bce example

I’ll see how the lab goes on Monday.


Like I’m A Kindergarten Teacher

A few years ago, I worked in a school that allowed every teacher that taught science to sit down for several days.  When I say every teacher I mean teachers from Kindergarten through high school.  It was an amazing experience and we were able to get a lot done.

What I remember the most was when the Kindergarten teacher would shake her head and say “I don’t teach science.”  we only talk about the seasons, the weather, how we breath faster when we run, sweating, laughing, and that batteries can go dead.”  We told her that was science.  She still shook her and said that she didn’t know how it was science, when she didn’t think it was science.

I think about this a lot; especially while reading some of the articles in Chemical and Engineering News and Physics today. I start reading the article, and then just shake my head and wonder how is what I teach my chem and physics students ever going to help them to understand some of the theories based upon these ideas?  I don’t even get some of it.

Maybe that’s what is needed.  A workshop that pairs research scientists with science teachers where all they do is discuss a couple articles published in a professional journal and trace the theories back to what is taught in a high school chemistry or physics class.

There is a subreddit titled “explainlikeimfive.  Perhaps, it could be something like that.  Except more like explainlikeimteaching it to a five year old?

Chemistry First?

I was helping my daughter with her biology the other night.  She is learning about activitation energy and how the role of an enzyme is like a catalyst.  I had to grit my teeth (not for the first time) as I read the text and its nice siimple explanation that a catalyst “speeds up a reaction” by “lowering the activation energy”.  I explained to her that isn’t totally true, but she needed to write it down as the answer to the question on the worksheet that had been copied from the workbook that goes along with the text (the title of the workbook was at the bottom of the copy next to the page number).  As educators, we know that it is more difficult to unteach a wrong assumption than to teach it correctly the first time.  This is not the first time this year I had to do this.

Yesterday, I related this traumatic experience to my coworker,  our biology teacher (my daughter does not go to the same school that I teach at), and she just smiled.

You see, most of our students take chemistry before biology.  Some of them even take physics concurrently.  So, as freshman, our students take a “Freshman Science” which is one quarter chemistry, one quarter biology, one quarter physics and one quarter Earth science.  When possible, the subject teacher is the one who teaches that science to the student in the appropriate science classroom.  Each quarter 20 – 25 students are each in the chemistry room, biology room, physics room, and Earth science room.  As the year progresses, the students move to the next room/teacher.  Once the basic lab techniques are learned, and the equipment unique to the subject matter is mastered, the students learn the basics of each class.

As sophomores, we recommend they take Chemistry (actually, we offer AP Chemistry every other year as a double block class, and this allows the students to be able to fit in AP Chemistry if they are willing to commit to the rigor of the class.)

So, Back to the title of this, Why not Chemistry First?  the mathematics are not more difficult than basic algebra, and as sophomores, they have yet to pick up very many bad Math habits, so stoichiometry can be taught and the fraction button on their calculator can be surreptitiously removed from the front of the calculator (not really, but I have threatened to do it with many a senior).  Their understanding of the “EE” button can be developed before they stumble upon the “carrot” button, so exponential values will be multiplied without mistakes.

As for the science, students will definitely understand the different molecules discussed in biology becuase they know what a molecule is.  The carbon cycle can be taught as a series of chemical reactions, and photosynthesis as an energy process might just be understood a little better.

Just a thought.  It works great for us.

double displacement reactions

trying something new….trying to build a particle model to describe precipitation reactions.  So far, students are  saying that drawing out the ions are helping them understand dissolving, combining reactants and possibilities for recombined products.

The use the solubility rules to determine which is insoluble.

Revisiting something old.  making them write down the rule that proves new molecule is insoluble.

Next up:  molecular; complete ionic and net ionic reactions.