Thanks Michelle for the project info--I too am very excited to work with Dr Judy on this citizen science project!
Our refractor seemed to have a bit of a grudge against us today: the line indicating salinity level simply refused to appear –though the kids were happy to pass it around peering in and trying to diagnose the problem (though I think we may need to seek expert advice).
Our secchi disk tests were a bit more successful; The kids were excited to help with a real-world project, and eager to take turns lowering the disk into the water. In fact, the later group got discouraged: why bother measuring the same thing again and again? This frustration turned into an unexpected opportunity to talk about the margin of error, and the power of multiple samples—a concept I wasn’t exposed to until college! But the kids got it instantly: if one of us is exaggerating, or needs glasses, or is impatient and stops too early—we could mess up the data! So having multiple samples helps us check each others accuracy.
The three groups got the following results:
Group 1: 4.5 (lengths)
Group 2: 4 (lengths)
Group 3: 4 (lengths)
Group 1: 3.5 (lengths)
Group 2: 3.5 (lengths)
These measurements prompted some great questions: why would water clarity change from day to day? What are the human and environmental factors that influence water quality? Is everything that makes the water murky actually "bad"? I look forward to exploring these any many other questions as we continue with the project throughout the summer.