Part 10 – Scientific Discovery

(The World Around Us)

Complete any TWO of the following

Explain what the major organs do in the human body, and how they work. These should be enough to cover/discuss –
  • Skin – protects our body and holds everything together
  • Heart – pumps the blood around to enable oxygen to get all through our body
  • Lungs – provides a way for oxygen in the air to pass into our blood
  • Liver – produces bile - plays a major role in metabolism and has a number of functions in the body, including glycogen storage, decomposition of red blood cells, plasma protein synthesis, and detoxification
  • Stomach – 1st stage of converting food eaten into energy
  • Kidneys – filters and excrete wastes from the body as urine
  • Brain – runs the whole body


Perform an experiment that has a chemical reaction. BICARB SODA and Vinegar in a film canister!

To do this experiment, the grey plastic film cannisters are great. Tip about half a teaspoon or so of Bicarb-Soda into the cannister. Add roughly a tablespoon of vinegar, put the lid on QUICKLY, and stand back. The top will pop. (if placed with the lid down, then the base will pop instead!)


Explain what has happened. The acid in the vinegar reacts with the sodium in the Sodium Bicarbonate, producing a salt (in the remaining solution - which of course will splash everywhere when it pops) and a gas – which expands in the container until there is too much pressure, causing the lid to “explode” off.


A mineral is a naturally occurring substance formed through geological processes that has a characteristic chemical composition, a highly ordered atomic structure and specific physical properties. A rock, by comparison, is an aggregate of minerals and need not have a specific chemical composition. Minerals range in composition from pure elements and simple salts to very complex silicates with thousands of known forms. The study of minerals is called mineralogy

Fossil fuels or mineral fuels are fossil source fuels, that is, hydrocarbons found within the top layer of the Earth’s crust.

They range from volatile materials with low carbon:hydrogen ratios like methane, to liquid petroleum to nonvolatile materials composed of almost pure carbon, like anthracite coal.

Fossil fuels are non-renewable resources because they take millions of years to form, and reserves are being depleted much faster than new ones are being formed. Concern about fossil fuel supplies is one of the causes of regional and global conflicts. The production and use of fossil fuels raise environmental concerns. A global movement toward the generation of renewable energy is therefore under way to help meet increased energy needs.


Talk about the minerals found in your area. Kaolin, a clay mineral can be found in limited quantities, but Sydney is mostly Sandstone, with coal below it - neither of which are minerals


Demonstrate how sound moves through air, water or a solid object. MAKE a Tin-Can & string intercom, and discuss how/why it works.
You need 2 empty & washed cans (about 825gms size). Punch a small hole in the centre bottom of each, and thread a long (2-3M) piece of string thru the hole of each can and tie the string off in the middle of them. Have the cubs stand apart so the string is stretched taut between them. They can then talk into them, and should be able to hear each other by listening to the sound from inside the can.

It works, because the sound waves are converted into vibrations in the can and then they vibrate along the string, then get converted back into sound waves in the can at the other end of the string. Even a quiet voice should be able to be heard if there is not too much other noise around at the time.


Make a sundial and use it to tell the time. To make a sundial you can take home
  1. Determine your latitude. Using a map for your area (or a GPS or Google earth etc), estimate your latitude (most road maps indicate latitude and longitude). Your latitude will be the number of south if you live in the southern hemisphere. (eg. Sydney=33 degrees south, so fold at the 35 line)
  2. Print this sundial construction template. This template was originally downloaded from NASA's website, but a recent concerted effort to locate it there again was unsuccessful. It is thus now hosted on my site - note I also had to correct some clock numbers which were incorrect on the original.
  3. Construct the sundial. You will need scissors and some tape. The more carefully you make the folds, the more accurate your sundial will be.
  4. Align the sundial. Take your sundial outside, place it on a level surface, and aim the style due North. You now have a working sundial! When you read the time, remember to take Daylight Savings Time into account (during Daylight Savings Time, the sundial will be an hour behind your clock).

Now that you have a sundial, here are some questions to ponder.
I think these also came from the NASA Page that is no longer there.
  1. When doesn't a sundial work?
  2. Does your sundial match your watch time? Why?
  3. If the earth rotates every 24 hours (approximately), how many degrees does the sun appear to move in one hour? In four minutes? (Hint: one full rotation of the earth is 360 degrees).
  4. The sun's diameter in the sky is about 0.5 degree. About how long does it take for the sun to appear to move its own diameter across the sky?
  5. Why don't we use local solar time instead of time zones in our everyday lives? Would it be easy to know what time your favorite TV program starts?
  6. Why do time zones generally run north-south instead of east-west?
  7. Does a sundial work the same north and south of the equator?
  8. What would be different about a sundial at the North Pole? The South Pole?
  9. Why didn't the ancient Egyptians use watches instead of sundials and obelisks?
  10. Would your sundial read the same time as another sundial 100 miles directly north of you? Would the shadows be the same length?


Measure the height of an object using the stick and shadow method


All you have to do is to stand a metre-long stick upright. Look at the shadow that it casts on the ground. Mark the length of the shadow then measure its length. Now measure the length of the shadow of the other item (eg a tree).

The lengths of shadows cast by the same light source are always proportional. For example, if the shadow of the metre stick is twice as long as its height, then the shadow of the tree will also be twice as long as the tree’s height. (eg –if the stick’s shadow is 2M, and the tree’s shadow is 12M long, we divide the length of tree's shadow by the length of the shadow of the stick, we get the height of the tree: 6M! Try it at different times.


Find north using an analogue wrist watch


1. Using an analog watch, point the watch’s twelve o'clock mark (the number 12) toward the sun. If your watch is set to daylight savings time, point the one o'clock mark toward the sun.
2. Bisect (divide in half) the angle between the twelve o'clock mark (or one o'clock mark if using daylight saving time) and the hour hand to find the north-south line. If you're unsure which way is north, remember that the sun rises in the east and sets in the west no matter where you are. In the southern hemisphere, the sun is due north at midday.


Find south using the Southern Cross Finding the Southern Cross.
This constellation is formed by five stars, withy the four brightest stars forming a cross that is angled to one side.
Identify the two stars that make up the long axis of the cross. These stars form a line which "points" to an imaginary point in the sky which is above the South Pole. Follow the imaginary line down from the two stars five times the distance between them. Draw an imaginary line from this point to the ground, and try to identify a corresponding landmark to steer by.
Another, possibly simpler, method using the Southern Cross is to also find the Pointers. This is a pair of two stars that point toward the southern cross in a fairly straight line. As above, find the two stars that make up the long axis of the Southern Cross. As well, look at the Pointers and imagine a line between them. Find the point in the middle of this line, and draw an imaginary line from that point at a right angle to the line. Where the line from the Southern Cross and the Pointers meet is true south.



© 2008 Ian Moggs - rights are given for copying and printing for personal use or use in cub-scout or similar groups.