Friday, April 19, 2013

Plants vs. Erosion

Anyone else notice how "vs." turned into a verb seemingly overnight? I have kids that write in their stories, "And then I versed Jimmy at soccer...." Kinda irks me. But anyway that has nothing to do with this post so I will save that gem of a thought for later.

My county recently revamped our science standards, and a major shift was made in our Life Cycles strand. We used to teach the basic life cycles - plants, butterflies, frogs, and grasshoppers - but now we only focus on plants, butterflies, and white-tailed deer. Yeeeeeah. Don't ask. I understand they wanted a mammal, and that they wanted to choose something that was prevalent in our state, but deer? Could they have possibly found anything with LESS available resources? Ummmm O.K. Aside from deer, the other major shift was that there is a much bigger emphasis on plants now. Yes they need the life cycle, but they also have to know about plants/crops that are native to our state, the importance of plants to humans and animals, what products come from plants, and the role plants play in erosion.

I decided this was a good opportunity for a messy science experiment. Of course me being me, I structured the "mess factor" in such a way that it really wasn't that messy at all. But the kids enjoyed it.

I gave each group of junior scientists two aluminum cake pans. One pan had a piece of sod at one end and the other pan had a scoop of loose topsoil at one end. Unfortunately I got so wrapped up in the lesson that I forgot to take pictures until most of the action was over :(

We first made scientific drawings of the two pans before starting the experiment and made comparisons of the two pans. Then the kids used "rainmakers" aka styrofoam cups with holes punched in the bottom, to rain over the grass-end of the first pan. Then they lifted up the pan to let the water run off and collect at the empty end of the pan. This was a good opportunity to review a few stages of the water cycle.

Then we repeated this process with the loose topsoil pans. The kids were really excited to see how the water washed the soil all over the pan. They spent a few minutes drawing their after sketches of the two pans and then discussed their observations. Obviously they noticed that there was less water filtered through the sod than the topsoil, and that the sod water was much cleaner. They also observed that most of the actual dirt in the sod pan stayed in place, where the topsoil washed and spread all over the pan. Because we had spent some time observing and discussing our results, much of the water in the sod pans was "sucked up" in to the sod. I hadn't expected this to happen, but it made for more interesting discussions.

Here are a few of their scientific sketches and conclusion statements:

In the end, we concluded that the roots of the plants helped keep the soil from washing away (yay!), so it was time to introduce the term EROSION, so they could have a proper name to go along with the phenomena they had just observed.  We decided to let our pans sit over the weekend and see how they had changed by Monday.

We had a great (and messy) time, and hopefully some of this will stick to their brains!

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