On 10/30/09, Rachel wrote:
> Ideas?

Most students have trouble understanding that air (or any
gas) has mass and volume because they can't see it. (This
still pops up at the HS level, surprisingly!) One way to show
this is to set up a yardstick that is screwed loosely to
another yardstick. Set it up so that the two yardsticks form
a T. Blow up balloons (contains the gas, because the ballonn
gets bigger as you blow) and attach one to each side...the
heavier balloon will pull the appropriate end of the
yardstick down. Using different size ballons shows that
different volumes affect the total mass of the same contained
gas. You could add a helium ballon to one side also. To show
the kids its 'really' helium, release it in the classroom
after removing it from the yardstick 'balance'. Kids already
know that helium balloons float, so now you can build the
idea that different gases have different mass.

Have students take the mass of common objects, including
liquids. Then build discussion to include if each of the
objects takes up space, which of course they do. SO, what do
all of these objects have in common...they all have mass and
take up space, just like the balloons...therefore all types
of matter have mass and take up space, whether they are sold,
liquid or gas.

Sorry if this may be too much for that level...I'm a HS Chem
teacher...

HTH!

Share This Post | Report This Post

Next Post >>

Posts on this thread, including this one