Thursday, March 22, 2007
why do we have water on earth? easy...
Every good experiment starts with a question...
4th and 5th graders brainstormed thinking of science questions they are interested in: "Why is the sky blue? What makes food rot? How fast do plants grow without water?"
An intense, quiet girl raised her hand and asked,
"Why do we have water on earth?"
WOW!!! This is advanced thinking- I was momentarily stunned...
A simple explanation for the bright girl...volcanoes, (she nodded as I drew gas from volcanoes creating a hazy atmosphere that would rain down things including water---we've already done experiments on the water cycle)Her next question? Why is there not water on other planets? (We talked about how Mars looked like it had volcanoes, but the atmosphere was closer to the sun, and may have burned off....and more about planets without volcanoes...)
We'll be making a pond muck battery (hopefully some will work- but if not, that's a good lesson too) I think we'll feed one with iron filings, one with molasses, one with both, I'm guessing the students hypothesize these will produce more electricity than just pond muck. (From me they know that some pollution is cleaned up by decomposers that eat sugar and that when iron spills in the ocean it sometimes feeds small organisms) Need to find a place to keep the stinky goop...as it popping the lid will only produce twice as much foul gas in the hot summer stickiness that is coming into our classroom.
The battery was a smashing success! Worked best with a voltmeter that could detect the faint current- amazing hope for the future of bio-energy sources. !!!!