The weather is a really important part of everyday life for many people and when it
comes to fairly extreme weather as we are having today, a lot of us are really interested
in how bad it is and how bad it's going to get. So you can see its absolutely pouring
down with rain at the moment. This is the tail end of the cyclone which is some distance
from here, but we're getting the after effects of it. We've had a 150 millilitres of rain
in the last 2 days and obviously we're getting a lot more today to add to it. So I thought
I'd take this opportunity just to talk about a really useful topic that you can adopt in
your classroom for teaching primary students and that is the weather itself and specifically
rain and measuring rain fall. Now rain of course is a liquid and so we might -if we
didn't know better we might assume that we'll measure the rain in litres, because that's
how we measure liquids. But of course that depends on the area of land that the rain
is falling on and so you can't just say, this is the number of liters of rain that have
fallen without saying over a certain area, so one thing I like to do is to do that sort
of calculation and say, well, on your house block or on the school grounds perhaps, how
much water actually fell? And the thing that I've been surprised with when I've done that
is it's amazing how much has fallen, and if you had to buy this much water, it would cost
you thousands and thousands of dollars, because obviously water has a cost with it. So this
free rain that we get, free water from the sky is an incredibly valuable resource. Anyway,
on to measuring the rain; this is one design, it's quite a common one in Australia for measuring
the amount of rain and of course what we're measuring is the depth it's got a funnel design,
so if I can balance the umbrella without getting wet, there's a funnel at the top, which is
a nice wide opening it's about 10 centimetres across, small opening in the bottom of course;
it flows in to this tube and inside that is a smaller tube and this has a multiplying
effect, so because of the size of the funnel, compared to the size of the tube, 1 millimetre
of rain falling thru the funnel becomes 1 centimetre of depth in the small tubes, so
there are markings on this tube that go up to 26 at the very top and that is 26 millimetres
of rain even though the tube itself is 10 times as high as that. So that allows us to
measure even quite small depths like half a millimetre is not difficult to measure with
an arrangement like that. So if you have an example of a rain gauge that you can show
your students you can investigate that with them. If you were to measure with just a straight
sided cylinder like an empty tin can or something like that, you could show the students how
difficult it is to actually measure the depth without some way of multiplying it in a form
like this. Let me just put that down. So there's quite a range of topics that you can investigate
with your students to deal with the amount of rain that's falling, as I've said, once
you've measured the depth then you could multiply that by the area knowing that 1 millimetre
of rain over 1 square meter will give us 1 litre of rain. So there's a nice simple conversion
that we can do and the other thing we can add to that is; 1 liter of water weighs 1
kilogram. So we can actually work out how heavy that amount of water is, and be very
glad that this amount of rain falling isn't falling in one big lump because it will too
heavy. Ok, so that's it for now, I'm gonna go inside out of the rain, I wish you well
with this topic with your students.