Having anticipated that all groups would decide that drinkable water was their number one priority for survival, we planned that the second unit would cover water analysis and water purification. Focusing on theses issues allowed us to cover the TEKS that dealt with solution chemistry - pH, boiling point, concentration, acids, bases, and salts. We also pulled in changes of state and transfer of thermal energy.
This unit was the first that would get into the substance of the project. I was a bit daunted by the task of trying to come up with a list of items from the cruise ship that the students would be allowed to use. It was a fine line between making the task solvable and challenging at the same time. For instance, we didn't want them to be able to use an aquarium filtration system, but we would let them pull out mattress batting if they wanted to use it.
The solution was another brainstorming session with Wendy Howe. This time another instructional coach, Phillip Lentz, joined us. Together, we devised a set of rules that would govern any materials that the students wanted to 'salvage' from the ship for the entire year. They could use anything they wanted as long as 1) they could justify its presence on a cruise ship, and 2) they were using it for something other than its original purpose. I would have final say on whether an item qualified under the rules. This transferred the burden of listing the items from me to the students and made the whole exercise more learner centered. It also allowed for multiple correct ways to solve the problem of water quality.
Wendy and I bounced around ideas about what we would give them to test. Our immediate thought was 'fish guts' but after consideration decided that we would rather 'contaminate' the water ourselves so we could keep it safe (no amoebas) and so we could control what was in it. We made two types of water - ocean and fresh. The ocean water obviously had salt, but it also had an oil slick from the wrecked ship. We put sand and coffee in it for particulates. The coffee also discolored it pretty well. Fish food made it sort of smelly. For the fresh water, we had previously decided that the island was volcanic for an upcoming geothermal energy unit, so we put powdered sulfur and sulfuric acid in the water. The water also included coffee and sand.
Neither type of water was perfect so the students had to make a judgment as to which type would be easier to purify. Part of the project required them to design a test that would identify the particular acid and particular salt in each type of water.
Some of the lessons I've learned from this project – there aren't enough clean beakers in the school (I've offered community service hours to the honor societies I return for dish washing). More importantly, after years of 'lab safety' tests, these students don't have any idea how to actually use a MSDS sheet when they are choosing the chemicals. They don't realize that they need to analyze the products of the reaction for safety in addition to looking at the reactants.
This serves to prove the point that the teacher doing the work, the thinking, and the planning doesn't really embed the learning about it in the students. There's no enduring understanding about how to work with the chemicals or how to conduct a chemical reaction safely.
Another thing we've learned is that Critical Friends is a crucial piece of the process. One group was just wrong about some of their test results, but were able to get on track by the time they had to present. Other groups were able to fine-tune their work and get a higher grade. The kids are pretty much brutally honest with each other, and are good about giving legitimate and constructive criticism.
Overall, I was pleased with the presentations and conclusions. Some of the groups showed truly inventive thinking about how they could implement their ideas with the limited resources on the island. Many students are already looking ahead and anticipating the next steps.
As for me, I'm looking forward to my room no longer being messy and stinky.
(Next up . . . Nuclear power!)
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