A requirement of the after-school program was that I had to teach at least two times during the week. I thought that I’d have a tough time meeting that while maintaining 40 hours at my real career, but I still agreed to a third class. How could I pass - it was close to home and on Friday, my day to work from home.
Almost all these K-2 students knew the three main types of clouds (cumulus, stratus, and cirrus) and the basics of the water cycle (water evaporates into clouds and precipitates down), but unlike the other two classes this week, they did not know about acid rain. I had the pleasure to introduce it to them.
To start, we measured the acidity of tap water. Most kids got a pH of 7 – perfect!
I added some vinegar to the tap water and all kids got a pH less than 7 – acidic!
On to rain water. Ah, the ideal opportunity to introduce the scientific method.
Step 1. Observe – looks like water doesn’t smell like the acidic vinegar.
Step 2. Predict/hypothesize: The students guessed it would be acidic and would have a pH less than 7.
Step 3. Experiment/test: All kids got a pH less than 7.
Step 4. Report: Our rain water was acidic – it was acid rain!
Third class for the week, and I don't think it could have gone better. Third time was a charm!
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