In the new curriculum is a unit on water. It includes information about the water cycle, how humans are interrupting the water cycle, a discussion of the fairly minimal percentage of Earth’s water that is actually drinkable and how humans seem to be doing their damnedest to make sure even that little bit is polluted. This is a perfect place to tie the curriculum back to New Haven, because New Haven is a coastal city that has 3 rivers running through it; the West River, the Quinnipiac River, and the Mill River. We will focus mainly on the Mill River, because part of what this piece will include is hands on work in one of the rivers, and we can walk to the Mill River from our school, though much of what is said about the Mill River is applicable to the other two and many other rivers as well.
Day 1: Watershed Areas
Have students look at historic maps of New Haven and identify all of the water - Mill, Quinnipiac, and West Rivers and the harbor. Students brainstorm using a topographical10 map where each river’s watershed areas are and then also where the water from each river goes.
Days 2 & 3: Water Pollution
Students use an article written by Melissa Denchak11 as a starting point. In groups, they look into the types of pollution we can expect to see in the rivers in New Haven. Once they have some ideas of what to expect, they can look at more articles: Yale Daily News from 197112, NBC Connecticut from 202213, New Haven Register from 201914, and also look for their own.
Days 4-6: Wikipedia
I love to use Wikipedia as a place to get initial background information, because while yes it is not considered a scholarly source, entries are typically written at a lower reading level than many scholarly articles, and the link-dense text means that students who do not understand a term or connection as they are reading are typically able to click and read and then continue. Additionally, the reference list is usually a helpful place for students to look for additional information.
The Wikipedia entry for the Mill River15 gives some information about historic industrial uses of the Mill River, and therefore potential sources of pollution, but I do wish it had more. While I will not have them submit them, this sort of lack in Wikipedia provides a great opportunity for students to then write their own Wikipedia entries that are more focused on the history and pollution of the Mill River. They will do this in pairs, as this sort of assignment is often overwhelming to students individually, and the partner approach also (usually) catches mistakes better than a solo approach. After students write their entries, they will trade and edit another group’s entry. Students will be able to do their own research, but will also be provided a few suggestions of topics and websites to look into to get started.
Days 7 & 8: Dichotomous Key
We will then switch gears and learn to use a dichotomous key. This takes some practice but is not difficult. We start by playing 20 questions (yes or no questions only) to try to identify a specific classroom object.
Example: If the object is a green spiral notebook on my table, questions might go in order: 1) Does it belong to a student? No. 2) Is it bigger than a desk? No. 3) Is it permanent? No. 4) Can one write with it? No. 5) Is it a book? Yes. 6) Is it a textbook? No. 7) Is it a book to write in? Yes. 8) Is it on a shelf? No. 9) Is it on the table? Yes. 10) Is it green? Yes.
Now, a dichotomous key is not exactly like 20 questions, because instead of yes or no questions, one provides multiple options and it MUST be one of them: ‘this or that.’ However, students enjoy playing 20 questions and it is close enough to help them get started with the idea. After a few rounds, we might then move into a version more like a key, in which 2 options are offered. In the above question 6, instead of asking about just a textbook, one could ask “Is it a book to read, or a book to write in?”
After this, students can go outside to take photos of 8-12 living things and make a key that they can use to identify those specific organisms. The first question would likely be “Is it a plant, an animal, or a fungus?” and continue from there, perhaps specifying whether a plant is a tree or a bush, whether the leaf edge is smooth or slightly jagged or deeply toothed, perhaps looking at colors of flowers, and other similar easily distinguished differences.
The last practice activity would be to project images of different species that we would expect to see at the mill river and then to have students use the actual key to identify them, first as a whole group, then in pairs correcting each other, and then as individuals. Before this happens, as a group, we would read over the key and discuss unfamiliar vocabulary as well as projecting examples of what each option looks like.
Day 9: Grading the River
Students will walk down to the river. In this instance, it will not be just me with one class for a period, but instead all of the 9th grade and their other teachers, and likely a few others, will head down for an extended period of time. If we can arrange it, we may take most of a day and have students working in shifts, some at the river, some cleaning up East Rock Park for service hours, maybe even some listening to a talk by one of the park rangers about something related to this unit. If not, this may take two hours or so from start to finish.
Materials Needed:
- Keys16 - printed in color and laminated to protect from water
- Data recording sheets
- Pencils (not pens, pencils will write when wet)
- Hip waders for adults going into the water (2-3 pairs)
- Nets
- Shovels
- Trays
- Buckets / bowls
- Magnifying glasses
- Forceps / probes
- Rubber gloves (if desired)
- Paper towels
I and the other adults going in will go into the water and use the shovel to stir up the muck at the bottom of the river. We then use the net to scoop as much muck as we can without breaking it. The scoop is transferred to the students’ trays, and they walk off to sort and ID their invertebrate specimens, leaving space for the next students to come get samples. As each group sorts their specimens, they are to use the key to identify each individual, and then tally the numbers of individuals on the data sheet. After they have identified an invertebrate, it is put into a bowl or bucket with a small amount of river water along with any non-living things such as rocks or leaves and any potential vertebrates like small fish, to return to the river when they are done. This last step is imperative as we do not want to disturb the ecosystem more than necessary.
Students will work in pairs or triples, both because it is easier logistically to not have 90+ sets of equipment, but also because it will likely make identification easier if students have someone to double check their identifications with. (Additionally, not every student will feel comfortable touching these animals, even with gloves.) Once each group has been able to tally the number of individuals of each species, we will identify the category each species falls into: very tolerant, tolerant, sensitive, or very sensitive. Once we know how many individuals (not species!) we were able to find in each category, we look at the percentage of all the individuals found that fall into each category, and use that to draw conclusions about the level of pollution that is present in the water.
It is likely that the Mill River Watershed Association17 or Save the Sound18 would be interested in the data we collect, as they are involved in efforts to clean up and protect the Mill River. If so, we will share the data we collect, as well as recording it ourselves so that years down the line, we have historic data to compare to. This would allow us to see if the water quality is improving, deteriorating, or staying approximately the same.
Note: This unit would not work well in the winter months! Additionally, we would expect to see different species and different life stages of the same species at different times of year, so if we want to be able to accurately compare historical data, we need to be careful to complete the specimen collection at the same time of year.
