Sunday, February 5, 2012
Warning: this post has nothing to do with cooking
Chemistry is a real part of our lives.
When I wrote this unit I wanted to make chemistry relevant to my students. Years back my school developed a collaborative process for unit planning that, while it is not required, is an excellent tool for planning a unit with teaching specialists (art, technology, etc.). Oh, and also a trained facilitator facilitates the planning process. (Is there a good synonym for facilitator? I couldn't think of one.)
This chemistry unit was planned with the art and technology teacher. In addition to using cooking as a lens for examining physical and chemical changes, our class has also worked with Vera, our art specialist, to examine how physical and chemical changes apply to art materials.
So far we have analyzed the medium of watercolors and how they come in solid and solution form. We crushed up a bunch of old, cracked watercolors, dissolved them in water and left them to dry in small containers. Some students squeezed liquid watercolors out of tubes that we starting to harden and left those to dry, too. And -- I thought this was the best one -- a couple students poured liquid watercolors into small containers and used a hairdryer to evaporate the water and leave behind solid watercolor.
Last Thursday we went to the art room, mixed up a bunch of plaster, and made hand print casts, the kind I remember doing in our utility room with my father when I was about three. Almost everyone agreed that plaster mixing with water is a chemical change because once it hardens, you can't get back to plaster powder and water. Everyone but one student who is positive that you can smash it up into little bits and do the whole process over again. This may be his independent experiment...
At any rate, when you mix plaster and water, it also heats up, but not for quite a while. This heat energy is another indicator of a chemical reaction. Kids got to experience this warming of the plaster late in the game, but the focus was more about them being little kids and playing with the plaster. Which is charming, in a way.
Friday we brought the two medium together and kids painted their hand prints with the watercolors we liquifies and reconstituted. A perfect Friday afternoon activity! And aren't these kiddos cute?