From: Meighan Bill (email@example.com)
Date: Mon Mar 10 2003 - 11:39:36 EST
In my general chemistry classes we start the year talking about the
scientific method and we do a demonstration lab where I perform several
of my best demonstrations. I then have the students write down as many
observations as possible for each demonstration and then they are to
write two hypotheses for each demonstration based on their observations.
Kids usually are not too excited about the scientific method but the
exciting demonstrations raises their interest level while they are
applying the scientific method. We then talk about the difference
between qualitative and quantitative observations and this leads into
measurement and significant figures. Measurement and significant
figures can be interesting if the measurement activities are
interesting. One activity that I have my students do is to find the
number of pounds of air in the room. I give them the density of air (in
grams/cm3) and a meter stick and let them go. The activity brings in
measurement skills, dimensional analysis, and significant figures. We
then compare the different answers that they come up with and see how
rounding the numbers differently can make a big difference in their
final answer. By covering measurement and significant figures early you
can reinforce the concepts every time that you do calculations and
measurements in the lab. The key is to hold kids accountable for
significant figures and good measuring skills for the entire course and
not just for that unit. When I first started teaching chemistry I
taught the topics but did not reinforce the skills throughout the year
and kids did not know them throughout the year. Now that I reinforce
them almost all of my students know the rules for significant figures
and use their measuring devices properly when in the lab. Every test
question that I have that involves calculations has a significant figure
point included and I tell kids at the beginning of the year if they
learn the rules it is like getting free points on the future tests.
There are always a few that refuse to learn the rules at first, but
eventually they get tired of missing points on every test because of it
and learn the rules.
From: Martha Harson [mailto:firstname.lastname@example.org]
Sent: Friday, March 07, 2003 3:23 PM
Subject: [Channel-talkchemistry] sequence of topics
I have been teaching chemistry for 24 years and have tried
various sequences. I've tried delaying significant digits, scientific
notation, and metric conversions until actually needed. But it seems to
work best for me to tackle those topics early on. The first week, we do
metric estimations and play metric mania. We do lots of easy labs where
we measure masses and volumes and calculate densities. I think it makes
things easier for students when we get to moles, etc. if the math skills
have been introduced before.
One thing that has helped my students is a list of "every time
questions". After each test, I have students mark the questions that I
consider to be most important. They keep a list of those questions.
They know that those same questions (with the numbers changed) will
appear on every subsequent test throughout the semester. We are on
block schedule and just completed the midterm test for spring semester.
It was just a compilation of "every time questions". Every single
student knew how to name compounds and write formulas and convert grams
to moles and moles to grams. That's quite an accomplishment for us
because we are in a low-economic rural area that does not generally
score high on standardized tests, etc.