This document provides instructions for several science experiments that demonstrate optical phenomena like refraction, surface tension, capillary action, and bioluminescence. It explains how these principles allow certain animals to see clearly underwater, walk on water, transport water long distances, and produce their own light in the deep ocean. The document also includes links to videos that further illustrate these concepts.

1. Tip: This experiment will work best on a sunny day.
1) Blow up a clear balloon but don’t tie it off. .
2) Push the black balloon inside the clear balloon
but make sure the opening to the black balloon
is still outside the white balloon
3) Blow up the black balloon until it is about half
the size of the clear balloon. Tie off the end
and push it all the way inside the clear balloon.
4) Tie off the clear balloon.
5) Use a magnifying glass to focus sunlight on the black balloon inside.
Challenge question: How could you use refraction to light your home without electricity?
Answer here: http://permaculturenews.org/2014/03/14/solar-water-bottle-bulbs/
and on YouTube: https://www.youtube.com/watch?v=kHTD_RX3J2I
You may have noticed lizards basking out in the sun in your backyard. Snakes and
lizards bask in the sun because they rely on an external source of heat to keep them
warm.
Tiger Snakes that live in cold
climates have adapted with
thicker and darker stripes to
absorb more sun.

2. The water strider has probably mastered one of the most surprising habitats. This
intriguing insect spends its entire life on the surface of the water.
Surface tension is a force which makes the
top layer of water stick together.
The water strider walks on the water because
its feet don’t break the surface tension of the
water.
Slowly and carefully take a paperclip and lay it on
the surface of the water. This may take a few
attempts. The paper clip can float on the water
because it doesn’t break the surface tension.
Dish soap will break the surface tension under the paperclip. If you have cotton
buds at home you can try it yourself. Dip a cotton bud in dish soap then inserting
it in the water without touching the paperclip. What happens?
If you want to make an explosion of colour using surface tension watch this
video: https://www.youtube.com/watch?v=mc5ljuG4FYE

3. .
Have you ever noticed that a droplet of water
splashed on a surface likes to stay in a bubble?
This is because all the individual water molecules
are attracted to each other
But if the water molecules stick to another
substance more strongly than they stick to each
other the shape can change.
When a narrow channel is inserted into water, the
water molecules stick to the edges.
Imagine you live in the deserts of Western
Australia. The sun is so hot that you have to
hide from it during the day. There are no trees
and only a few sparse shrubs so your only
escape is to burrow underground. You are safe
from the heat but you are growing thirsty.
Where could you possibly find water in a
place like this?
Luckily, you are a Thorny Devil, a small lizard with spiny scales who is adapted for this
very environment. Your impressive scales hide your secret: A network of tiny channels
that can move water from the ground to your mouth via capillary action. All you need
to do is stand on it.

4. Plants have been using capillary action to take water from the ground for
much longer than the Thorny Devil.
Plants get most of their water from the soil, which is accessed by growing roots
deep into the ground. The roots deliver the water to the leaves and flowers.
With the help of an adult, use a knife to cut the
bottom stem tips of several (at least three) sticks of
celery at a 45-degree angle. Be sure not to use
scissors as they will crush the stem.
Put the celery in a vase
Add 1-2 cups of water
Add about 25 drops of red food colouring
Leave your experiment to run for about a week
Check in everyday and record the appearance of
your celery on the next page

5. Get your coloured pencils ready! Over the next few days you will need your red and
green pencils to record what happens to your celery. If you are particularly good with
technology, you might prefer to take photos.

6. Have you ever noticed that objects look distorted when they are under
water? This is because light bends as it moves through one substance to
another (such as from the water to our eye). This bending is called
refraction. How far a substance bends light is its refractive index.
Fish eyes have adapted to have the same refractive index as water. Light
doesn’t bend when entering the fish eye so they can see everything exactly
as it is.

7. When humans are underwater, light bounces on the edge of the eye. This
makes underwater objects appear bigger than they actually are. Place a spoon
or straw into a glass of water and watch how it appears to fracture.
In your pack you will find a small satchel of clear beads. When hydrated these
beads have the same refractive index as water. Place about ¼ of a teaspoon of
the beads into a clear glass bowl or vase. Add about a litre of water and leave
overnight.
What do you see?
Challenge question: How could you use refraction to light your home without
electricity?
Answer here: http://permaculturenews.org/2014/03/14/solar-water-bottle-bulbs/
and on YouTube: https://www.youtube.com/watch?v=kHTD_RX3J2I
(The arrows show
the passage of
light from the
straw to your eye)
Light bounces on the edge of the glass

8. Sunlight can only travel a limited distance through water. This makes the deep ocean a
very dark place. However, some animals have adapted by producing their own light.
This is called bioluminescence.
Bioluminescence is used by some squid, jellyfish, microbes, crustaceans and fish. This
light is used for camouflage, defence, communication and illumination.
Bioluminescent light is the product of a chemical reaction, When two chemicals mix,
they react and produce light. This is the same type of reaction you might have seen in a
glow stick.
Take out your glow stick in a dark room. Gently bend the glow stick until you hear a
snapping sound. This sound is from a tiny glass cylinder inside which released a
chemical to mix with one in the tube. The reaction of the two chemicals produces light.