Friday, October 21, 2011

Deeper Nature Study: Stalking Bacteria in the Wild Part 1

Nature study is the core of many a homeschooler's science studies.  Nature study for the younger set is often simple and un-directed; the children find what they can find and bring it to Mother for examination, or home to observe and preserve.  The child and parent try to identify specimens, and often learn how to use a field guide together.  It's fun and informative for the younger children, but what about older kids?  Just as highschoolers can benefit from intensive copywork using great books and technical articles, so a high school student can get laboratory credit for nature study that is specific and directed towards a more quantitative goal.

This year, I chose a few victims (I mean students, of course) to try out an addition to our biology curriculum using more advanced living books.  This is the first in a short series of blogs on "Deeper Nature Study."

A few years ago, I came across a terrific book called A Field Guide to the Bacteria by Betsey Dexter Dyer.   Dyer is a biology professor at Wheaton College in Massachusetts, and has recorded a Modern
Scholars lecture series on this same topic called Unseen Diversity, which is top-notch and available from Audible.  Both are fine alone, but combined they make a formidable mini-course in bacteriology that is easily used by homeschoolers.  You will be relieved to hear that Prof. Dyer suggests that we not grow things in petrie dishes in our kitchens, so we won't; instead, we take our search outside.  In the wild, we have been able to discover evidence of bacteria everywhere.  And we are only 1/3 the way through the outdoor portion of the course.

The best thing about this short series of hikes is that it can be done anywhere, almost any time, with little modification.  Since bacteria are plentiful everywhere, and very few are pathogens, it's a safe and nearly fail-proof study.  You can study bacteria where you are, because they are there, too.

We began with a brief lecture on different kinds of bacteria, and the environments in which each thrives.  A quick version--cold, temperate, and hot are three measurable but wide temperature ranges for bacterial growth (one can get way more specific, and we did, but I don't really want to write out the entire lecture, and Prof. Dyer does it in more depth).   pH is another variable for determining the types of bacteria we are likely to discover.  The third environment we are exploring varies in oxygen content.  We could also add salt, and more, but these are the basics.  After my brief lecture we went outside and found some regular every-day common clover to examine.  We dug up the roots to find nodules of nitrogen-fixing bacteria in the root system.  These are terribly EASY to find!  We found some lichen, that combination of fungus and bacteria that grows so well on rocks and tree trunks.  And we found some cyanobacteria growing in patches large enough to identify by color alone.  Then we hopped into the car and took a quick field trip to the local Quaker cemetery, where the old tombstones yielded more evidence of bacteria at work.  And that was day 1!  NB:  It is very difficult to pry teens out of graveyards...go figure.

Day 2 brought us to a local swamp, where quick running water, deep muck, and hard trails all had perfectly detectable bacteria for our viewing--and sometimes smelling--pleasure:
The light leaf litter smells fresh even though it is full of bacteria.

Miss A. is encouraged to take a deeper will have a different odor.

Right along the trail are worm castings, full of bacteria fresh from  the gut of  worms.  Slugs approve.

Intrepid Miss B. strives for the best sampling spots, mid swamp!

OK.  Crossing the swamp by log is just fun for Miss B., Miss C.,  and A.

Slow, clear water reveals a nice bacterial mat, with large air bubbles!

Miss C. discovered that the faster running water was cold.

Yet, who could resist? Neither P nor Miss B.

Bubbly beer-like bacteria!!

Ha-ha!  Miss M. captures millions of bacteria.

Tempting...but no, she didn't.  ;)

Next stop?  The salt marsh...

1 comment:

Spinneretta said...

OOh, this is a good one :) My fondest memories of biology in school and college were those field trips in which I was sampling. I loved quadrats, transects and pond dipping... and getting the teens outside is always good :)
Personally *I* think it looks fun too ;)