biomass energy experiment + lesson

We're getting into the thick of our latest Inquiry focus, all about types of energy. All of the teachers on my team have chosen one type of energy to teach and we're setting up rotation lessons for the classes. With seven of us, this could take awhile...! But I love the idea of sharing the teaching and getting to know some of the other kids in the hallway. 

For my energy type, I'm teaching about biomass as a renewable source. Because some classes can only come in for a 45-minute block, I've started each lesson off with a really cool experiment involving biomass energy at work. Basically, I put this slide on the ActivBoard and let the kids get to work:

Note: I handled the warm water part as it had to come from a kettle.

We let that work away as we discussed the energy sources in these pictures:

This led to some great discussion. But then I asked if they knew that things like cow poo, bananas, sewer water, and corn could produce electricity. A lot of them looked at me like I'm crazy. We talked about what these things have in common and were able to come up with a definition for biomass. 

Biomass is any material made by plants or animals that we can convert into energy.

Next, their attention was quickly drawn to the experiments they had left sitting on the windowsill, and what we saw was this:

So cool! We talked about our observations, reviewed our predictions/hypotheses, and came to the conclusion that the materials inside reacted together to create a gas. Pretty smart, these third graders!

Once we decided that the living creature in the bottle was indeed the yeast, I set it up for them as if the yeast was going through a morning routine, not unlike the routines we all might go through. When we're just looking at a  little yeast granule, he does not look alive - in fact he's asleep. To wake him up, we put him in a soothing warm water shower. And how do we all feel after first waking up in the morning? Hungry! Just like our yeast. So we give him a little breakfast of sugar, and as he starts munching away, he begins to burp, letting out little bits of C02 gas, just as we do when we exhale. The kids quickly concluded that it's this carbon dioxide that rose up in the bottle to inflate the balloon. (PS - These little C02 burps are the same reason we have little air pockets in our bread!)

To show the kids some ways that biomass is actually being used throughout the world, I put an iPad at each table team with instructions to find a certain video and they rotated to watch some different examples:

This one was a hit with all that poop...

There are tons of videos out there with great examples.

As they watched, I asked the groups to be thinking about the pros and cons of biomass energy. When they thought of one, they added it to a whole-class T-chart:

By the end of the rotations, this board was Filled!

This was a good way to continue discussion about biomass energy and for eventually comparing various forms of energy. When my class had learned about geothermal energy with another teacher, we asked them to "lay it on the line" by choosing whether they thought geothermal or biomass was the most sustainable choice for energy use. (This is a great Visible Thinking routine called Tug of War.) They moved to the designated side of the room and voila, we had a great tool for debate!