Kindergarteners in Motion

Today at Primaria I did Newton's first and second laws of motion, much
as I did them at the elementary last fall.  If you read that entry, I
followed that plan up to and including how the Moon is attached to the
Earth by gravity.

Before doing that, I did a quick advertisement for the
tornado-in-a-bottle building activity I want to do next time.  We had
earlier, in the context of pressure, shown how water will not fall out
of a straw if you hold your finger over the top.  This is because for
the water to get out, air would have to get in to fill the space.  But
air can't get in when your finger is over the top.  So today I brought
in a giant size version of this: two 2-liter soda bottles screwed into
a connector, with one half-full of water.  Turn it upside down, and
the water doesn't fall because the air need to switch places but get
in each other's way. Now the cool part: swish the water around and it
forms a "tornado" which allows the air to go up through the center
while the water swirls down around the outside.

I bought plenty of the connectors and my goal is to collect enough
bottles to allow each kid to make one at school (with the option of
food coloring and glitter in the water!) and take it home.  Parents,
please bring in empty 2-liter bottles!

I bought the connectors (40 for $40) at teachersource.com.  I
recommend you try somewhere else because they took forever to ship,
and when I got them I found out that they leak.  I was able to prevent
leakage by wrapping the bottle threads with masking tape first, but I
shouldn't have to do that.  I went cheap because I wanted a large
quantity.  If you just want one or a few, Artec Educational has a
clear one (so you can see what's happening through the connector) for
$2 each.