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These S&P lab sheets have been modified for clarity.

S&P Modified Lab Sheets (Word documents in a ZIP file)

Here are two PowerPoint presentations that have been configured to work like the game show Jeopardy, to help students review the material in Solutions & Pollution:

• S&P Jeopardy 1
• S&P Jeopardy 2

Sharon Reuter identified the following recent news stories as relevant to Solutions & Pollution:

• “If Vanilla and Cinnamon Spread Quickly, UW Researchers say, so can Toxins; the Sound is Flavored by the Holidays,” Seattle PI, 12-25-2006
• “The Down Side of Clean,” Science News for Kids, April 2, 2003
• “Deluge of sewage left in storm’s wake“, Seattle PI, December 6, 2006.
• “A modern chemical is now found at the top of the food chain,” Seattle PI, October 10, 2006
• “The message in the (plastic) bottle is dire; material absorbs pollutants and becomes part of the ecosystem“, Seattle PI, 10-10-06.

How much red dye is left in each cup when you dilute the 10% solution seven times, each by a factor of 10?

One misconception that students can develop from this lab is that there is no red dye left in the cups where it can’t be seen. They calculate the concentration of red dye in each cup, and see on the EPA charts that even a 1PPM concentration can be harmful to organisms’ health depending on the chemical.

So how many molecules of FD&C Red #40 are in each cup? To find out, I started with the assumption that 10 drops of food coloring is 1mL and has a mass of 1g. You can adjust the following data by whatever % necessary to correct for any error in this assumption.

Water’s molecular mass is 18 (2 H, 1 O). 1 mol of water has a mass of 18g, so 1g of water has 3.34444×10^22 molecules (calculated by dividing Avogadro’s number, 6.02×10^23 by the molecular mass of 18).

FD&C Red #40 has a formula mass of 496, so by the same calculation, 1 g of Red#40 has 1.21371×10^21 molecules. That’s 1.2 sextillion molecules, in 10 drops.

In 1g of the solution of 10% Red#40, which is what Solutions and Pollution provides, there are 1.21371×10^21 particles of the molecule. If that is the mass of 10 drops, the cups have the following numbers of molecules of FD&C Red#4:
1: 1.21371E+20
2: 1.21371E+19
3: 1.21371E+18
4: 1.21371E+17
5: 1.21371E+16
6: 1.21371E+15
7: 1.21371E+14
8: 1.21371E+13
9: 0 (control)

The solution generally becomes colorless around cup 6, and students may think that it therefore has no red left in it. If you evaporate the water, though, you can see traces of the red in cup 6. These traces represent 1.2 quadrillion molecules, which illustrates just how small a molecule is.

Solutions and Pollution Inventory

A few reflections on lab 8 from S&P:

Students did not understand what type of observations to record in the data table. If I were to re-make this data table, I would include a column for each specific observation I wanted the students to make.

Many students said the precipitate came from nowhere, rather than saying that it was formed by the chemical reaction between the iron chloride and the sodium carbonate.

It was common for the iron chloride solution to have some specks of iron in it, even after stirring. The precipitate formation is still obvious, but perhaps the results would be more dramatic if there were no solids in the small cups to begin with. One way to solve this problem and simplify this lab would be to make up an iron chloride solution before hand, and give it to students in bottles. Or, you could have students filter the iron chloride solution, which would further illustrate the difference made by the precipitation reaction (i.e. it lets you filter out something that previously went through the filter).

I will be leading an initial use training for Solutions & Pollution on November 9 from 4-7PM, probably at JSCEE. Sign up with Kathryn Kelsey if you’re interested.

Update: I have a class that conflicts with this date and time. The workshop will either be rescheduled, or it will be led by someone else.

I’ve done a lot of thinking about the Solutions & Pollution module, and the first few lessons don’t go into the depth I would like, nor are the lab sheets straightforward enough for my students to follow. So, I made the following documents to use instead:
Particle Model for Dissolving (my own design, based on the transparency in lab 1)
Particle Model for Filtration (also my own design)
Lab 1 sheet - Filtration (also in MS Publisher format)
Lab 2 sheet - Solubility (also in MS Publisher format)

The lab sheets are simplified and put in more concrete terms. One difficulty of the lab sheets provided with the curriculum is that they are ambiguous as to where students should record their data and responses. This is intentional, to allow teachers some flexibility, but I prefer to specify in writing where students should write their responses, since it’s hard enough to get them into the mindset of writing everything down.

If you’d like these documents in Publisher 2003 format, email me.

Note: The lab sheets are designed to be copied two to a page and pasted into science notebooks/journals, which I find is a good way to a) keep students organized, and b) reduce notebook setup time - every kid can glue, but not every kid can copy a procedure and make a data table in a reasonable amount of time.

One more resource: This is a great explanation of how sewage is treated. I’m going to have all of my classes read it.

Here are the conceptual story documents that give an overview of the Solutions & Pollution module, with references to the AAAS Atlas and Washington State EALRs.

Part 1 (also PDF)
Part 2 (also PDF)