Priscilla (Scill) Chan

Biography

Scill Chan is an 8th grade math and science teacher at the Tompkins Square Middle School (I.S. 839M) on the Lower East Side of Manhattan. She majored in Environmental Science at Harvard University, specializing in urban and environmental justice issues.  She participated in the Undergraduate Teacher Education Program in partnership with the Harvard Graduate School of Education and did her student teaching at Fenway High School in Boston, after which she earned certification as a General Science teacher for Grades 5-12 in Massachusetts.   She is currently earning her Masters in Environmental Science at Hunter College.  She can be reached at chanscill@yahoo.com.

Students are assigned, in groups of four, to a plot of land roughly one meter square (available from neighborhood gardens or lots).  Their task in September will be to identify, using the web and guidebooks, the different elements which interact in this plot (plants, weeds, insects, birds,  humans, etc.)  As the students learn in the classroom about Earth Science and the elements which affect the topography of the Earth, they will also apply and experiment using these variables on their plots.  For example, when learning about the effects of wind, students might experiment about the productivity of their top soil as compared with soil from lower depths.  This coordinated classroom-plot learning will continue throughout the year so that students investigate different elements in every season, producing a very substantial image of how one particular plot of land in NYC changes in relation to the time of year.  (Note: Although the activities appear in order in this mini-unit, they should be appropriately spread throughout the year to correspond with seasonal changes and classroom curriculum.)

Materials: large butcher paper, pencils, pens, rulers, coloring instruments, cameras, and nature guidebooks

In the summer, inquire at local neighborhood gardens or vacant lots about the possibility of having students come and visit these plots and get permission to minimally alter them (take small samples for experimentation).  Choose suitable plots of roughly one square meter and assign students to them, in groups of four.  Take trips (at least 2) to these plots, introducing students to the idea of stewardship and observation of the plot.  (While at the plots, use pencils and string to stake out the borders.  Remove them at the request of the lot/garden owners.)   During these visits, students have to create a birds' eye view map of their respective plots, including as many natural elements as possible (including specific colors of plants, location of dead/alive bugs, human footprints, etc.).  Encourage reference of the nature guides to help identification.  Students should date and save maps.  Have them compare plots with each other.  Which has more diversity?   Put these maps into a journal, which the students will add to all year-round.

Materials: pencils, pens, index cards, coloring instruments, string, nutrient-free agar, bacteria "food" (try a mixture of water and tuna or bouillon cubes), wire loop, soil, microscopes, tape, heat source, funnel, paper towels, plastic bags to collect leaf litter

After your students have a good sense of what's in their plots, have students draw these elements on index cards and discuss their interactions with each other.  Use the string to connect the links in these self-created food webs, allowing for ample visibility of how intricate the connections are.  Most likely none of the kids will come up with bacteria as part of their soil webs.  Take some soil and a nutrient-free agar plate.  Spread a ring of "food" around a bit of soil and wait a few days.  Look under the microscope to see the bacteria which crawl out of the soil.  Or you can grab a bunch of leaf litter, put it in a funnel whose mouth opens to a wet paper tower.  Turn on a heat source right above the litter and wait a few days!  You should see small critters emerge from the litter onto the paper towel.  Look under the microscope for closer analysis!  Have the students look back at their original webs and edit them.  What else should be in there?   What do these bacteria do?  Tape these webs onto paper and include it in the student's plot guidebooks.  Discuss the role of bacteria in ecosystems.

Materials: cold and heat source (ex. freezer, heater), plastic bags, soil from plot, agar (try unflavored gelatin), petri dishes, glass spreaders, paraffin (try tape)

Make some petri dishes with a mixture of agar and nutrient (experiment to get the right mix!).  Take a bit of soil and mix it with distilled/boiled water.  Take a few drops and put them on your agar plates.   Spread it around with the glass spreader (dip it in alcohol to rinse it off); make sure no liquid remains on the top of the agar.  Close the dish, and seal it with paraffin or tape.  Make as many of these plates as you want to test different temperatures.  Be sure to label each plate (grease pencils work best!).  Then, putting these plates upside down, pick a hot/cold/RT source and leave the plates (for example, leave one on a heater, one on your desk, and another in the freezer).  After a few hours, compare growth.  Wait a few more days, compare growth (don't wait too long, mold will strike!).  If you have enough growth, have students count colonies of bacteria and graph the data.  What is the right temperature for these soil bacteria to grow?  How do we know this?  You can repeat using different temperatures or using more or less concentrated soil bacteria mixtures.  Discuss what it means to have comfortable living conditions.  What would happen if these bacteria were permanently subjected to a different temperature?  What about animals, plants, humans?

Materials: various spices and other germ-killing substances (alcohol, lysol, fruits, vinegar, etc.), tweezers, water, flame or alcohol, hole-punched lens paper disks, petri dishes, nutrient-rich agar (or try agar and a mix of bouillon cubes)  

Discuss what students think about when they hear the words germs, bacteria, microorganisms.  Talk about how most of these organisms are actually helpful.  But for those that are harmful, antibiotics need to be used to kill them.  What are antibiotics and how do scientists test them?   Have students come up with a list of ideas of chemicals/substances they have in their homes or see in the classroom that they think might kill germs.  Have students choose three of these substances and prepare lens paper disks that are saturated with this substance (mix the substance with water if it is a powder).  Be sure to use tweezers which are sterilized after touching each substance in the flame or with alcohol.   Exercise caution.  Spread some soil bacteria (or other source) all over the plate (as described in Activity #3).  Then place the disks in the center of each plate (to reduce the number of plates, have the students divide their plates in quarters and use the last quarter for a blank disk (discuss the idea of a control).  Leave at room temperature (or on a heater) for a few hours.  Check growth.  Which substances did not allow bacteria to grow around them?  How might scientists make conclusions from these observations?  If you had to do the experiment again, what might we change?

Materials: straws, scissors, soil from plot, rulers, pencils, paper, fast-sprouting seeds (any variety)

Discuss the idea of erosion and topsoil.  What happens to land that can no longer sustain an adequate amount of life?  What is desertification?  Visit each plot and have students use straws to collect an appropriate amount of soil from various levels (mark off the straw in inch increments and stick it in the soil, to retrieve your soil, pinch off the straw above the level that you want and just shake it - collect the soil in plastic bags). This will take time but the students will have fun.  Collect about a 1/4 cupful of soil from each level (amount 5 straw retrievals).  Be sure to label each bag (4 inches below ground, 3 inches, 2, 1, surface, etc.)  Bring the bags back to the classroom and spread them out, sprinkling seeds throughout the soil.  Wait a day, then check to see how many seeds have started sprouting from each soil level.  Is one level richer than another?  What does the soil provide the plant?  How do you know?  Compare your results with another plot.  Graph your data and put these graphs in your log. 

Materials: soil from plot, egg yolks, paper, plastic cylindrical containers (like water bottles), light source, water

Discuss where students think the first elements of life came from.  If your students have already studied Evolution, you can trace the timeline back to these microbes and re-emphasize how short a period of time humans have been on Earth.  Ask about the conditions that the seeds in Activity #5 needed to sprout.  Does all life need these elements?  What about extreme environments (low oxygen, no light, etc.)?  How might other organisms live that is unlike ours?  Visit the plot and have students collect a tube of soil.  Build a Winogradsky column using this soil (do any internet search on Winogradsky column for more detailed information about this fascinating experiment!), by first layering the container with paper and eggs (to serve as cellulose and sulfur).  Sprinkle a little water on top, and leave it near a light source (sunny window is fine!).  Wait approximately 2 weeks and students should start to see multi-color bacterial colonies grow.  Discuss an anaerobic environment vs. an aerobic one.  Why is the Winogradsky column important for telling us what lives in the soil?  Why is it important to tell us what types of life there are on this planet?  Refer back to the food webs the students created in Activity #2.  What type of food web is going on in the Winogradsky column?  How is it different/similar to the ones in your plot? 

Materials: water, soil from plot, stopwatch, small graduated cylinders, smooth rock or anything else to pound down soil

Following Activity #6, discuss the importance of air pockets in soil.  Why might some organisms prefer loose soil?  Why might other organisms prefer more compact soil?  (This is a great place to bring in a worms unit, if your students like working with live animals!)  Have students collect a large container of soil from their plots (about 5 cups worth).  Separate the soil into smaller cups.  Explain that they are going to pack down the soil to see how much water can be absorbed, depending on how packed the soil is.  Pack each cup with the rock a different number of times.  Label your cups (for example, pounded 20 times, 15 times, 10, 5, 0, etc.).  Then pour in the same amount of water into each cup (a good amount of water, like a large cup), wait about 5 seconds (shorter/longer if you like).  Quickly pour out the unabsorbed water from the top of the cup into a graduated cylinder (if you don't have enough cylinders for each cup, then you should do each cup separately).  Measure the amount of unabsorbed water and graph the data.  Students should see that soil can hold a lot of water, but that when it is packed and there is no loose room, it cannot.  Discuss what happens when excess rains cause floods (water run-off).  How useful is soil?  What happens if you cut down a whole forest and put in a paved parking lot?  Where does the rain go?  

Materials: oil, pond water (or water with fertilized soil), cylindrical containers, rulers

Watch a video about oil spills and the devastation they cause.  (If you have time, have students replicate a small community using feathers, rocks, plants, etc. and then cause a mini-oil-spill.  Let students spend some time cleaning the oil, how effective are their efforts?  how difficult/timely is the process?)  Talk about the role of oil in the world, what is it, where does it come from, what are its natural uses?  Explain that some bacteria consume oil.  Be sure to illuminate for students that most bacteria in the world are helpful, and this is just one example of their great uses.  Have students fill the cylinders with pond water and a bit of fertilized soil (or if you don't have access to a pond, try any source that has bacteria.  A very informative professor told me that if we're saying that these bacteria are naturally-occurring, then they should be in many places!)  Drop in a bit of oil at the top.  Measure the thickness of the oil layer and record that data in the student logs.  Then leave them aside for a week.  There should be a cloudy layer formed between the oil and the rest of the water, to indicate some decomposition.  If you have enough of a layer, students can make a mount of this tiny layer and look at it under the microscope.  Measure the thickness again.  Record the data.  Leave for a few more weeks.  Keep recording data.  How long does it take to have the entire layer degrade?  Is this fast/slow, compared to the size of the bacteria?  What does this say about the possibility of natural remedies to environmental disasters?

Please view the accompanying Museum investigation that focuses on the differences between natural and anthropogenic change.  The visit is most easily adaptable at the end of a basic Earth Science introductory unit that has covered seasons, ecosystems, and the weather.  It involves a 4-page Museum search packet which the students, in their teams, split up and complete cooperatively.  They then re-group in their teams and explain to each other what they've learned at the Museum.  The investigation describes how the visit correlates to the curriculum described on this website and how this unit addresses NYC learning standards.  (The picture shows the display board used to describe the Museum investigation to my colleagues.)  Please visit the Museum of Natural History website for up-to-date information about their Education programs.  It is an excellent and amazing place to learn with students.

http://www.treebranch.com/nosc/community_gardens.htm - information about urban gardens in NYC

http://www.greenmap.org/nyc/ - great eco-resources in NYC with kid-friendly maps

http://www.nycvisit.com/content/index.cfm?pagePkey=224 - possible field trips in NYC

http://www.nycas.org/ - NYC Audubon Society

Many thanks go to the staff and facilitators from the Woodrow Wilson National Fellowship Program, Pace University, and the American Museum of Natural History.   Your advice was invaluable for developing this project and the accompanying Museum investigation.  Thank you for a very memorable and engaging experience.

Even more thanks go to my colleagues at the Institute!  Your patience and willingness to work with me exceeded my expectations, and I was eager to learn from all of you.  I would not have gained as much from this program had it not been for our awesome camaraderie.  Best of luck with your investigations, and please keep in touch!  Yay protista! :)