Tuesday, June 26, 2012

Oh Yeah, I Have a Job

I have not had a school thought since May 25.

Haven't even missed it.

My plan this summer was to spend a little bit of time every day and get ready for school in the fall*. I have so many things I want to do differently that I simply can't wait until August to start fixing them unless I want to ed up in a straight-jacket somewhere.

So it's been a little bit of a struggle getting back into chemistry mode today. I am back at a short Modeling Workshop this week looking at the new chemistry units 4, 5 and 6 that were revamped last year. The old sequence just kind of skimmed over quite a bit of crucial information but still expected kids to figure it all out. The new units go back and add in a little bit of filler to help bridge the gap from macroscopic observations to more microscopic.

Unit Four discusses the difference between mixtures and compounds. The Modeling still skims over those in a series of demonstrations/notes that didn't do it for my kids. I added in a mixture identification/separation lab last year to help kids visualize and practice those techniques. Plus they needed the practice. My kids come to me with horrible lab skills and this is an easy one for them to practice with. There was also a general consensus about kids not being able to recognize a mixture, pure substance, element or compound in a particle diagram. I had a hard time trying to figure out how in the world I messed up this section so badly that they couldn't do that, but apparently it wasn't just me, so I am not sure where this confusion comes from or how to clarify it. To me, it seems so simple, but apparently to teenagers, I might as well be teaching string theory.

Then we get into the law of definite proportions and the law of multiple proportions. The transition from relative mass to the mole is much smoother and I think it flows a little better for kids. They still have a hard time with using the relative masses to show the laws, but that is something I can help them through fairly easily. I have an idea for a lab, but it is not fleshing out as completely as I'd hoped. I'll come back to that.

We still have a few issues to hammer out tomorrow, namely the idea of how the molar masses of the elements came about. We spent a good amount of time today trying to figure out how to do the calculations on Worksheet 1 in Unit 5 and we still did not come away with a clear understanding of how to explain it. Basically, it compares several elements' mass ratios in their oxides to each other and in turn compares those masses to the mass of hydrogen in water. The problem is that hydrogen does not combine in a 1:1 ratio so it throws all of our calculations off. We can't seem to find a way to explain how the ratio is accounted for in the calculations in a way that doesn't seem to say "just believe me". If I can't get a grasp on it, how am I supposed to expect kids to?

So question for you....how do you explain relative mass? Does anyone out there have an amazing activity that lets the kids manipulate stuff? If you do, please share.

Have any of you done a test run with the new materials? How did it go? Did you do anything amazing to help kids get it? ASU (and I) would really like some feedback about any problems or successes you may have had!

*Looking back, this seems that this is my plan every summer. How is it that I never seem to get this done???


Jason Stark said...

RE: Unit 5 Worksheet 1

When we went through this in my workshop last summer, we struggled with relative mass as well. The best solution we could come up with was to add H2O2 (hydrogen peroxide) to the list of substances in the table, which has that 1:1 ratio, making the relative mass pretty much match up with the molar mass.

Find my updated version here:

Tracie Schroeder said...

Hey Jason
Thanks for the tip. We will try doing that today!

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