====== The Water Cycle ======
There is a fixed amount of water in the world that’s been here since the beginning of time. The water in your tap is the same water that the dinosaurs drank millions of years ago. [[https://shoalwater.nsw.gov.au/Community/Tapstar/Kids/The-water-cycle|How is this possible]]?


{{ youtube>hehXEYkDq_Y?640x360 |The water cycle - How it works}}
=== Video 1. The water cycle - How it works (2min)===
  * **IF YOUTUBE FAILS, TRY VIEWPURE:[[http://viewpure.com/hehXEYkDq_Y|The water cycle]]**

[[http://beyondpenguins.ehe.osu.edu/issue/water-ice-and-snow/common-misconceptions-about-states-and-changes-of-matter-and-the-water-cycle|Common Misconceptions About States and Changes of Matter and the Water Cycle]] - [[http://static.ehe.osu.edu/sites/beyond/penguins/downloads/assessment-probes/how-much-water-probe.pdf|Assessment question]]

Gaseous phase is one of the four fundamental phases of all matter along with solid phase, liquid phase and plasma. Gases can be clearly distinguished from solid and liquid phases because, unlike in solids or liquids, the atoms are in free motion and are spread all around a container. Gas and vapor both seems similar due to their transparency, but are two distinct phases that matter can exist. The key difference between gas and vapor is that gas exists only in one physical state whereas vapor can coexist with another physical state. ((Gas vs Vapour - http://www.differencebetween.com/difference-between-gas-and-vs-vapor/))
  * Water will evaporate from every wet surface - even from wet air!
  * Clouds are visible masses of water vapour.
  * Fog and mist are falling water in gas or vapour form.
  * A [[https://en.wikipedia.org/wiki/Vapor|vapour is different from an aerosol]]. An aerosol is a suspension of tiny particles of liquid, solid, or both within a gas. Water condenses into visible droplets (aerosol) after evaporating from a cup of hot tea.
  * Atmospheric water vapour is found near the earth's surface, and may condense into small liquid droplets and form meteorological phenomena, such as fog, mist, and [[https://en.wikipedia.org/wiki/Haar_(fog)|haar]].
  * Water vapour is responsible for humidity.


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====== Water on Earth ======
[[http://www.globaleducation.edu.au/verve/_resources/GEP_Primary_Water_Resource_Aug12_NSW.pdf|Water on Earth]] is a free, teacher-friendly resource for Australian Primary Schools. Published by: Professional Teachers’ Council NSW, Science Teachers’ Association NSW and Primary Teachers’ Network (Global Education Project)
© Commonwealth of Australia, 2011.

{{ :learn:heat:water-cycle:water-cycle-01.png |Water on earth - The water cycle}}

For each topic and activity, it includes:
  * Specific Australian Curriculum references
  * Teaching focus information
  * Background Science 
  * Global education perspective
  * Reference to common student misconceptions
  * One or more simple classroom build-and-play activities

====== Activities: ======
One fact to point out to your children is that the droplets on the side of the bag are clear, not blue. When water evaporates, the blue food colouring (or whatever) is left behind.

The [[http://www.differencebetween.com/difference-between-gas-and-vs-vapor|main difference between gas and vapour]] is that gas exist only in one physical state whereas vapour can coexist with another physical state.

=== Terrarium ===
  * National Wildlife Federation - [[https://www.nwf.org/~/media/PDFs/Be%20Out%20There/Schoolyard%20Habitats/WaterCycle-NWF2011.pdf|Water Cycle (Build a simple terrarium)]]

=== Solar Still ===
  * ABC Australia - [[http://www.abc.net.au/science/surfingscientist/pdf/lesson_plan09.pdf|Solar Still - Lesson plans]]

=== Water Cycle In A Bag ===
  - [[http://www.cleanup.org.au/PDF/au/clean_up_australia_plastic_bags_factsheet-2017.pdf|Before you start, see 'Say no to plastic bags']]
  - [[https://www.playdoughtoplato.com/water-cycle-bag/|Water cycle in a bag]]
  - [[http://www.arcticclimatemodeling.org/lessons/acmp/acmp_58_WaterCycle_WaterCycleBag.pdf|Water cycle in a bag and cup]]

**Q:** What is **collection** in the water cycle?

**A:** Collection refers to **the process** by which water gathers back into bodies of water such as rivers, lakes and oceans. This begins with precipitation, when water falls from the clouds in the form of rain, snow, sleet or hail. A lot of the time, precipitation falls directly into a body of water, but at other times, it soaks into the ground, where plants, people and animals end up drinking it as ground water. Most of the water will end up leaching back into bodies of water through the soil

According to [[https://shoalwater.nsw.gov.au/Community/Tapstar/Kids/The-water-cycle/Collection|Shoalhaven Water]], the total water supply on the Earth is about 13.7 billion cubic kilometers, but the vast majority of it (about 97 percent) is oceanic salt water, while the rest is fresh water. 

Because it is not possible to consume salt water, and because desalinisation is both time-consuming and costly, it is important for humanity to maintain a clean supply of fresh drinking water.

Current farming and consumption practices are placing much of the fresh water supply at risk. One example is the Ogallala Aquifer, which sits under much of the American Midwest. Irrigation by farmers in the Midwest is draining this aquifer, which could take as long as 6,000 years to refill, according to Mother Earth News, as no one has discovered a way to hasten the collection process.

=== References ===
  * Detailed [[https://www.youtube.com/watch?v=al-do-HGuIk|Water-cycle documentary]]
  * Pearson's - 'Water-cycle' [[http://www.futuresparks.org.au/media/20852/pearson_science_7_sb_chapter_3_unit_3.3.pdf|(recommended DoE NSW/Scootle)]]