One thing can lead to another. In science we call this a cascade. Sometimes cascades are good. When we cut ourselves, a cascade of biochemical reactions leads to clotting and we don’t bleed to death.
One thing can lead to another in a series of bad effects. Sedimentation is one of these unfortunate cascades.
We filled in a 3X3 grid of ways that sediment might lead to fish dying. Some of the squares stand alone– for example, sediment can clog the gills of fish directly, much like a smoke filled room makes it difficult for lungs to work. This square also brought up the important point that aquatic organisms breath oxygen that is dissolved in the water in little bubbles– they do not separate the oxygen from water. The “O” in H2O is not for breathing.
Other squares were connected to each other in some way. The effect of temperature on metabolism is one example. Warm water holds heat and when fish are warm their metabolisms increase because they are poikilotherms (“cold blooded” in elementary school lingo) and their temperatures change with the environment. Higher metabolism increases the need for oxygen– and we now realize there is less DO in sedimentous water.
Getting all the causes down takes some studying. Start now to build fluency since the list is high in concepts.
We have new wiki posts with new opinions about just how much of the fish demise is related to sediment versus acid rain or chlorine.
In other news: Science symposium project ideas were due! Printed!
We’ve run into run off over and over as we have sought the cause of the fish deaths. The next problem to consider is that the run off is carrying soil into the water.
Researchers test water clarity by dropping a disk under the surface and then raising it until it can be just barely seen. The depth of the water is measured to this point. We did a variation using a disk and string– and just marked high, medium and low sediment. When sediment is high, clarity is low. When sediment is low, clarity is high.
We still have to figure out where the soil is coming from, and exactly why it might kill fish. One thing we do know is that plants lower erosion quite a bit.
On another topic, science symposium 2015 has launched! We read the introductory parts of the handbook and it’s time to think of a project.
We have a special time with each of the 2-3 classes to do science! They are learning about water too.
For this late October/early November series, we did drops on a penny with them. They did several trials, considered variables, and described what they observed.
Drops on a penny illustrates two important properties of water: water is cohesive– it sticks to itself and water is adhesive– it sticks to other things. Water’s stickiness is responsible for the way life on earth evolved. It has also driven the need for some inventions like towels and windshield wipers.
Today was a day to pull things together.
We had a pause from completing the analysis on acid rain while we collected data on macros from the Casparkill. With a “data backlog,” we really had to take stock and do some synthesizing.
My job was to write questions that were not easy to answer just by reading or even looking at a graph of data. Students’ job was to tackle the toughies. It worked out quite well.
We had three terrific classes with Jen Rubbo from the Institute of Ecosystem Studies and Elizabeth Ruiz, the post-baccalaureate intern for the Casparkill, from Vassar College.
We started with a pre-trip visit. Elizabeth explained her job and what a watershed is. Jen used an activity to explain dissolved oxygen and conductivity. Students wrote hypotheses about how leaf pack macroinvertebrates (macros) would differ between riffles and pools.
The second day we were off in the field. We collected physical data like dissolved oxygen content, conductivity and temperature. We also looked a living factors by using nets to collect macros. There was time to explore and we were lucky to be able to use high waders to go deep.
Third day was in the lab. The leaf packs were opened. We had data to compare from last year– fewer caddisflies [:( ] than in previous years. On the upside, many, many planaria– that Emma is going to try to save for grade 6. And, one pack had the biggest leech ever brought in by middle school students at PDS.
There’s more to do with these data….
Juan Tuno is back on the case!
This time, he is having us look into acid rain as a problem in the area. Acidity is measured on a scale called the pH scale. To test the waters we used pH paper and matched the color after it was dipped in the waters from the rivers in the Gray Area.
Here is what the buddy classes looked like. Data analysis to come, but it sure seems like we saw more male scientists than female from the young artists.
We slowed down and stayed in one place long enough to dig into those mysterious files that were left on Juan Tuno’s doorstep.
They are the strangest bunch of documents that most students have ever had to take notes on. For example, how do you take notes on emails between two people? How do you take notes on the cleaning schedule for the water slide? The news clippings were a little more straightforward, but they were not about the Gray area!
Whenever you take notes, it is key to know what the important information is. The detective part requires studying the information carefully enough that you can decide what is critical to write down. That’s the inference part of reading– you have to figure out the information that is not being told to you directly.
The second important part of the chlorine study is the comparison of the numbers of Daphnia counted upstream and downstream from the water slide. How is Juan Tuno able to construct a controlled experiment using a natural setting? It’s hard enough to make a controlled setting in a lab (just think of the drops on a penny). But how does a scientist do that on a stream? There is a way…
Finally, there is the whole E. coli business. Homework will help clear that part of the mystery up, as well as a little explanation in class.
We were busy.
We introduced three citizens from the Gray Area through a dramatic reading of statements: Juan Tuno, Don Juan Tuno, and Avery Wun. They each have different points of view.
Next, we got ready for our first visit to a 2-3 class. Sue has matched us up with buddies. To get to know each other, we found where we live on a map of the Hudson Valley.
We asked the buddies to “Draw a Scientist.” Every 2-3 drew as detailed a picture as possible and then wrote a sentence about who the scientist was and what the scientist was doing. The caution to the 7 mentor: while encouraging as much detail as possible, don’t use pronouns! We’ll see the result of our experiment after we visit all of the 2-3 classes.
When we got back to the lab, we had a second dramatic reading, of the board of supervisors meeting of the Gray Area. Juan Tuno (science boy wonder) is concerned that the water slide park is going to be shut down because the fish are dying. He doesn’t want the slide blamed unless it actually is killing the fish. He’s got a little family conflict with his uncle, Don Juan Tuno…
So, Juan Tuno did some research, and so did we. Using Daphnia from a healthy stream (the control) and comparing that to samples from upstream and downstream from the water slide, we can use the Daphnia as a bioindicator of the health of the water.
And then there are those mysterious files left on Juan Tuno’s doorstep…
The history of an area can tell us much about what might be affecting the environment.
So, today we read “clue cards” with tidbits of information about the last 100 years of history in the Gray Area. Students put the clues on a timeline. That way it made it easier to analyze recent changes since they can affect the health of the fish.
After processing all the clues, we moved to the class wiki. Students wrote individual posts that stated their opinions about what is killing the fish. The great feature of a wiki is that after writing a post, writers can comment on the posts of other students in the class. Sometimes students disagree with each other. (Imagine!)
Get ready. The situation in the Gray Area is of such great concern that a board of supervisors meeting has been called.