Thoughts on our Fall Science and Service Day
Maple, elm, sycamore, and oak leaves filled the bags. Little hands and big hands raked, piled, tossed, and disappeared into the mostly dry and brown sun-catching devices. By mid-November most of the pigments in these exotic broad leaves (there are few native hardwoods in the Palouse/Northern Rockies region) had broken down. The leaves were now shells of their former selves. The chlorophyll had given way to the carotenoids – the reds (anthocyanins) and yellows (xanthophyll). They in turn yielded to the tree’s determination that it was now time to completely sever the connection between twig and stem, returning every bit of available nitrogen back to its core, to serve as critical nourishment and antifreeze for the winter.
Some reds still remained in the occasional mountain ash, yellow in an aspen or cottonwood scattered around town. They stood out with brilliance on this last of the sunny days of a relatively mild autumn.
Trees are marvelous provision. On this day alone they provided us with work, an activity to undertake with friends new and old, apples for cider, and material for discovering more about pigments and how they work. Using paper chromatography we were able to get a snapshot into the various pigments present in different leaves. We learned that different pigments have different molecular weights, allowing the wicking alcohol to separate and deposit the lines of color on strips of coffee filter varied distances from the edge. Download this activity and try it at home (brighter colors work best).
Fall Leaves Paper Chromatography
One young homeschooling father piled leaves into a bag with his two and three year old sons. Upon leaving he commented something to the effect of “many hands actually get quite a bit done, far more than I expected. This was awesome. I learned a lot.” He wasn’t referring to raking, which he has most certainly been doing for over twenty years. And he wasn’t referring to the chromatography which was yet to come. I think he learned much, much more.
