water

Water
Two Hydrogen atoms plus one Oxygen atom = water  H2O
water is a good solvent which means  it is good at dissolving 
things . Hard water has some minerals and metals in it and 
soft water has very little minerals and metals in it. Every living
thing on earth has needs water to live. 

Water  cycle
The water cycle is a cycle in which water goes through . it is like this

    
                          
snow melts
from the
mountains         (  )and Rains
    / \                   |  |               then the water evaporates and turns into clouds
  /----\   ________|________  ______________
/         \  ________________ \|                             |
            and turns into a river \                               |
                                               |                              |
                                               |                              |
                                               |_______________|
                                                 that empty's into the ocean
The water cycle was on from the time of the dinosaurs . So you might be drinking the same water the Dinosaurs drank !

Water Pollution
Is waste and other bad stuff that goes on water. Water can usually take care of pollution in three ways

Dissolving
In this method the water dissolves the pollution.

Dispersing
In this method the water Spreads out the pollution so no one area will get affected badly

Recycling  
In this method the water recycles or makes the pollution food for other organisms

The water can get polluted in lots of ways like sewage waste or factory waste
When the water gets polluted there is no Oxygen for the living things in the water.
When the living things die other micro living things that don't need Oxygen come
in and make bad smelling gases .


Floods
Floods are a natural disaster that happens when land gets more water than it can absorb.
Lakes ,rivers and rain can make floods. Big waves made by earthquakes can also make floods.
Floods can do a lot of destruction like washing away houses and drowning people. People can stop floods with dikes , levees and dams.




Source : Brainpop

Classification and fish

Classification
Classification is a way of grouping living things. Today their are 8 main levels called taxa they are
                                                     Least specific
                                                        Domain
                                                        Kingdom
                                                        Phylum
                                                        Class
                                                        Order
                                                        Family
                                                        Genus
                                                        Species
                                                     Most specific
 The Domain is three groups called Eukarya . Bacteria and Archaea .
 The Kingdom has 6 groups which are Animals, plants, fungi, protists, eubacteria and archaebacteria.
  The other groups have a lot of groups in them. Lets take the Gold eagle for example.

                                                        Domain: Eukarya All life forms that are not Bacteria or Archaea
                                                        Kingdom: Animilia All animals 
                                                        Phylum: Chordata Backbone animals
                                                        Class: Aves Birds
                                                        Order:Accipitriformes Most birds of prey ( see Raptors)
                                                        Family:Accipitridae hawks, eagles, kites, harriers and Old vultures
                                                        Genus:Aquila Eagles
                                                        Species: Chryaetos Gold eagle

                                                        Name: Aquila Chryaetos Gold eagle

Fish
Are the largest group of vertebrates. Most are Cold Blooded. All have gills. Most have scaly body and fins. They use their fins and their streamline body to cut through the water.  There are three main fish groups

Bony fish
Are the biggest group of fish.
Bony fish have skelotons m-
ade of bone. Most have a
swim bladder a sack in th-
eir body that controls their
depth and height in the water


Cartilaginous fish
 are fish like sharks and rays.
Their skeleton is made of cartilage.
Cartilaginous fish have the biggest
brains of any other fish. They also
have tiny teeth on their skin

Jaw-less fish
These fish have no jaws they eat by sucking . They are Ancient fish


Source brainpop