We make 6 at a time and the kids help me. The science in the mixing and
feeling the temperature of the balls as they start the chemical reaction
with the molecules and the balls heating up is fascinating...and I want
them to "feel" that.
I don't know what exact size it is, but I use the middle sized coffee
can...not the biggy. I pour two cans of plaster and two cans of vermiculite
into a plastic bucket. I mix this up really well while a student gets
warm/tepid water (2 cans also) and pours it in. We stand around a
newspaper-covered table while I mix it for approx. 5 mins. and it just
starts to thicken enough for it to kinda hold together. Quickly I "pour"
the mixture out on the table into 6 piles while each student picks up
"their" ball and starts to form it. This takes only a matter of minutes.
They lay them on another newspapered area for approx. 5-10 mins. They are
really cool and slimy until this period and then they start to heat up.
Kids get to feel this action and they think it's really "neat".
I can do this process 5 or six times within a class period (other kids are
working on the previous project still) and get everybody done (up to 36
balls) and STILL have time to clean up within 43 minutes. Of course, I'm
ready to go when they enter the classroom. Tip...make extra balls for those
that might crack, break, absentees, etc.
The balls are left out for a day or two before we carve. Carving is done
outside under a tree. I usually do this project during the springtime.
Takes a good 2-3-4 weeks to dry in a warm place. Toodles.....
Bunki Kramer - Los Cerros Middle School
968 Blemer Rd., Danville, California 94526