Wednesday, July 28, 2010

Is It Living?: Glue Critters

Duco Cement - Duco Cement
This is a fun demonstration, but it does require some slight of hand, so you'll want to practice a bit before your big performance. 

Set a Petri dish (or another transparent container) filled with water on an overhead projector. 

Place a tube of Duco cement in a brown paper bag. 

Tell the students you're going to release a critter into the Petri dish.  Carefully, squeeze a few small drips of glue into the dish.  Make it look like you're pouring something out of the bag - don't let them see the tube of glue.  Play it up!

After a bit, add some pencil shavings to the dish - the critter will "eat" them. 

What happens if you add a drop of soapy water or dip a bar of soap into the water?

And then for the big question: are the critters alive?  What evidence do you have?  How can you explain it? 

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