Tuesday, June 19, 2007
Voice of Experience
The following is an excerpt of a post from one of NY's most dedicated and experienced Regents Chem teachers, Mr. Mark Rosengarten. He nicely summarizes some of the common errors that his past students have made; learn from this list and avoid these errors on Wednesday (forewarned is forearmed!):
I have been focusing on those areas for the last 15 years
to figure out a way to make those topics more accessible for the
students. Know what I found out? Those kids who take the time to learn
it do just fine. Here are the specific weakness areas I have been
addressing, that show up in item analysis year after year after year:
1) Molecular formulas. The kids have the most trouble remembering how
to determine the molecular formula given the empirical formula and the
molecular mass. Most of it stems from a refusal to just acquaint
themselves with the definitions of empirical and molecular formulas,
because if you understand the definitions, the calculation makes all the
sense in the world. One thing that throws them is that a molecular
formula can sometimes be an empirical formula, and unless they really
are good at knowing how many bonds an atom can form and take that next
step to actually drawing the molecule, they continue to be confused
despite my continued efforts to refine how I present it and how they
work on it.
2) Mole-mole problems. Again, despite endless refining of teaching
methods here, students often do not make the connection between
mole-mole problems and the use of the coefficients of the balanced
reaction. We start off with the analogy of making pancakes, and we use
a recipe's ratios to scale the recipe up or down before we move on to
the mole-mole problems.
3) The difference between molecular polarity and bond polarity. I have
even split the two topics up into completely different units and bring
it together. They always want to go with the symmetry. They look for
the easy way to remember, and that does not always work.
4) Colligative properties. You would think this is a simple game of
simply memorizing that boiling point goes up and freezing point goes
down when solute is added, and the effect is magnified at greater
concentrations. I show them the chart on the antifreeze container, show
numerous videos, do demonstrations, but it comes down to them just
remembering!
5) Electrolytic cells. Ever since my song "You Start At The Anode", my
kids have become champs at voltaic cells, but they simply do not get
electrolytic cells. I have a fuel cell car model that includes an
electrolytic hydrogen generator that I use to model the process, but
they still cannot grasp the concept.
6) Natural decay reactions. They are excellent at them when reminded
(endlessly) how to do them, but test them on it (write the decay
reaction for I-131) and they will write the half-life. If they do
actually write what looks like the decay reaction, they put the decay
particle on the left side. I have demonstrated this using a nerf foam
ball gun...the gun with the ball represents the unstable nucleus, then
you draw the arrow...then I fire the gun to show the decay particle
exiting the unstable nucleus, and that the two particles are now
separate. I show them video clips of the process. Makes no difference.
7) They are champs at nuclear fusion (Why Does The Sun Shine, by They
Might Be Giants, does a great job at this), but they cannot for the life
of them remember artificial transmutation or fission, or the fact that a
tiny bit of mass is destroyed in the reaction and converted into vast
amounts of energy. Tried about a million things to get this across.
8) Atomic number and mass number, what they mean and how to find them.
Same goes for nuclear charge, number of electrons in an ion and the
charges of the subatomic particles!!!! This is simply studying. I have
come at it from all different angles to try to appeal to everyone's
learning style, but it slips through their minds like some vague
slippery thing. Given them practice, and throughout the year.
9) Half-reactions for diatomic species. Even my honors students have
difficulty with this. I approach it by using drawings, basic
configurations, dot diagrams...any way I can explain it, I tackle it.
They have a very hard time with it.
10) Acids and bases...just the fact that acids yield H+ ions and bases
yield OH- ions confuses them to no end, despite the Reference Tables and
repeated demonstration and evaluation and diagramming.
11) Electrolytes vs. nonelectrolytes. Acid solutions and ionic
solutions are electrolytes, molecular solutions are not. End of story.
Acid formulas start with H+ or end in COOH, ionic compounds contain a
metal and nonmetal or polyatomic ion, molecular formulas contain all
nonmetals. DOH! I bring the concept of electrolyte and nonelectrolyte
to most units, starting from day 1. I don't know how else to teach
them. I have to say that this year the students have done much better
with it than ever before, due to massive repetition of the concept.
WHY? Because charged particles in motion can carry electrical charge.
If they are not in motion (ionic solid) then they can't carry charge.
If they contain no ions (molecular) them they cannot carry charge.
These seem to be the main ones I contend with. There are other smaller
issues, but I chalk most of the others up to a lack of doing assigned
work, inattentiveness and copying off of other students' papers. If you
don't DO, you don't LEARN. Pure and simple.
Mark
Each year, Mr. Rosengarten hosts the Regents Review Live show on public television and he also provides other chem teachers with a lot of instructional materials. Kudos to him; let us heed his words and put in the ultimate effort on Wednesday's Chem Regents.
I have been focusing on those areas for the last 15 years
to figure out a way to make those topics more accessible for the
students. Know what I found out? Those kids who take the time to learn
it do just fine. Here are the specific weakness areas I have been
addressing, that show up in item analysis year after year after year:
1) Molecular formulas. The kids have the most trouble remembering how
to determine the molecular formula given the empirical formula and the
molecular mass. Most of it stems from a refusal to just acquaint
themselves with the definitions of empirical and molecular formulas,
because if you understand the definitions, the calculation makes all the
sense in the world. One thing that throws them is that a molecular
formula can sometimes be an empirical formula, and unless they really
are good at knowing how many bonds an atom can form and take that next
step to actually drawing the molecule, they continue to be confused
despite my continued efforts to refine how I present it and how they
work on it.
2) Mole-mole problems. Again, despite endless refining of teaching
methods here, students often do not make the connection between
mole-mole problems and the use of the coefficients of the balanced
reaction. We start off with the analogy of making pancakes, and we use
a recipe's ratios to scale the recipe up or down before we move on to
the mole-mole problems.
3) The difference between molecular polarity and bond polarity. I have
even split the two topics up into completely different units and bring
it together. They always want to go with the symmetry. They look for
the easy way to remember, and that does not always work.
4) Colligative properties. You would think this is a simple game of
simply memorizing that boiling point goes up and freezing point goes
down when solute is added, and the effect is magnified at greater
concentrations. I show them the chart on the antifreeze container, show
numerous videos, do demonstrations, but it comes down to them just
remembering!
5) Electrolytic cells. Ever since my song "You Start At The Anode", my
kids have become champs at voltaic cells, but they simply do not get
electrolytic cells. I have a fuel cell car model that includes an
electrolytic hydrogen generator that I use to model the process, but
they still cannot grasp the concept.
6) Natural decay reactions. They are excellent at them when reminded
(endlessly) how to do them, but test them on it (write the decay
reaction for I-131) and they will write the half-life. If they do
actually write what looks like the decay reaction, they put the decay
particle on the left side. I have demonstrated this using a nerf foam
ball gun...the gun with the ball represents the unstable nucleus, then
you draw the arrow...then I fire the gun to show the decay particle
exiting the unstable nucleus, and that the two particles are now
separate. I show them video clips of the process. Makes no difference.
7) They are champs at nuclear fusion (Why Does The Sun Shine, by They
Might Be Giants, does a great job at this), but they cannot for the life
of them remember artificial transmutation or fission, or the fact that a
tiny bit of mass is destroyed in the reaction and converted into vast
amounts of energy. Tried about a million things to get this across.
8) Atomic number and mass number, what they mean and how to find them.
Same goes for nuclear charge, number of electrons in an ion and the
charges of the subatomic particles!!!! This is simply studying. I have
come at it from all different angles to try to appeal to everyone's
learning style, but it slips through their minds like some vague
slippery thing. Given them practice, and throughout the year.
9) Half-reactions for diatomic species. Even my honors students have
difficulty with this. I approach it by using drawings, basic
configurations, dot diagrams...any way I can explain it, I tackle it.
They have a very hard time with it.
10) Acids and bases...just the fact that acids yield H+ ions and bases
yield OH- ions confuses them to no end, despite the Reference Tables and
repeated demonstration and evaluation and diagramming.
11) Electrolytes vs. nonelectrolytes. Acid solutions and ionic
solutions are electrolytes, molecular solutions are not. End of story.
Acid formulas start with H+ or end in COOH, ionic compounds contain a
metal and nonmetal or polyatomic ion, molecular formulas contain all
nonmetals. DOH! I bring the concept of electrolyte and nonelectrolyte
to most units, starting from day 1. I don't know how else to teach
them. I have to say that this year the students have done much better
with it than ever before, due to massive repetition of the concept.
WHY? Because charged particles in motion can carry electrical charge.
If they are not in motion (ionic solid) then they can't carry charge.
If they contain no ions (molecular) them they cannot carry charge.
These seem to be the main ones I contend with. There are other smaller
issues, but I chalk most of the others up to a lack of doing assigned
work, inattentiveness and copying off of other students' papers. If you
don't DO, you don't LEARN. Pure and simple.
Mark
Each year, Mr. Rosengarten hosts the Regents Review Live show on public television and he also provides other chem teachers with a lot of instructional materials. Kudos to him; let us heed his words and put in the ultimate effort on Wednesday's Chem Regents.
# posted by C @ 1:29 AM 
