B Barber
Science Coordinator

Science

"Wetlands Show" (Junior)
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Program: St Jude's 24th of March, 9.45 to 10.15am (Junior school).

Equipment: several tables, 2 plastic cups, acid, base, lime water, bicarbonate indicator, universal indicator, turbidity tube, thermometer, 7 conical flasks; 6 beakers & 1 jug (+chemicals); animal flash cards; OHP and screen; lab coat.

1. Program notes:

"Hello everyone! I'm Professor Cludd and I am looking for my friend Ralph … anyone seen him? … we'll look around for him later. What do you think? Anyway, we're here to talk about water. Why is water so important to us?

1. So we can drink;
2. So we can wash ourselves;
3. So we can clean clothes;
4. So we can cook…

Yes. That is true! Many other uses as well.

I have been sent on a special secret mission to St Jude's … top top secret. Can you keep a secret? I have been told that you guys have a wetland at the back of the school. Is that true? You not lying to me are you?

Scientists say that fresh water is our most valued and sought-after resource. In other words … its very important to us all. What would we do without water? I know I might smell after a while because I didn't shower. We would always be thirsty and we couldn't go swimming without water. How awful! But we need to keep it clean and look after our water supply.

Where does it come from? (sky, clouds, lakes, dams etc).

Sometimes though the water supply is not very clean or safe for us to use. When we build more buildings we sometimes pollute the water in the rivers and dams. Sometimes in water that looks clean it may have harmful things in it like too much sediment, salt, not enough nutrients or even toxic chemicals! It could affect human health, harm wildlife and limit food production. The entire area from which a stream or river receives its water is called a catchment area. When it rains, the water drains naturally to the lowest point on the land, forming into small creeks that feed into larger streams and rivers as they run downhill. This collects in the catchment areas. It is then ready for our use in our homes.

Sometimes rivers and streams can be polluted. Scientists test the water of these streams to see if the water is safe for humans as well as other animal life in the streams. What type of life lives near your wetlands? Have you seen these? Or these? [Flashcards]

Scientists test the water for a number of things …

a. Dissolved oxygen … the type in air that we breathe. The less there is the more life that must be in the water using the oxygen.
b. Temperature … this affects the amount of energy plants can get from the sun and how small water creatures can fight disease.

Experiment: "Water temperature"
Display a thermometer. What is it?

c. Turbidity … how dirty the water looks. It is really dirty then creatures at the bottom of the stream cannot feed.

Experiment: "Turbidity"
Equipment: cloudy water and turbidity tube.
Fill the turbidity tube with dirty water to show how it works.

d. Salinity … salt … too much salt is not good for anyone!

Experiment: "Salty water"
Equipment: 2 cups, normal water, salty water.
Get two students to taste a cup of normal water and one with a lot of salt in it. Which is salty?

e. pH testing … this tests for acidity … which are chemicals that can be quite dangerous!

Experiment: "Acid-water-base"
Equipment: acid, base, water, 3 conical flasks, universal indicator.
Universal indicator into 3 large conical flasks with acid, water and base. Talk about safety and do not drink liquid even if it looks like water.

So be careful … not everything that looks like water is water.

f. Nutrients … without them pond life cannot exist.
g. Phosphorus … this helps organisms gain the energy they need everyday.

Just for fun … I will show you some other things to note about chemicals like water."

Experiments:

Equipment: several tables, acid, base, lime water, bicarbonate indicator, universal indicator, 7 conical flasks; 6 beakers & 1 jug (+chemicals); animal flash cards; OHP and screen.

a. Lime water: Two conical flasks with lime water (Na2CO3) and water. Two students blow with straws and the lime changes to orange from red. Shake the orange one and it may return to red (with a stopper in it?).
b. Bicarbonate indicator: Blow into conical flask and watch it change colour.
c. Lime water: Blow into conical flask and watch it change colour. Add acid and it goes clear again.
d. Water-wine-beer-milk: Great little demo!