Animals eat plants, releasing carbon dioxide into the atmosphere and water
Decaying animals and plants are made up of carbon. Ancient animals and plants eventually become fossil fuels such as coal
The sun emits sunlight that travels to the earth. Co2 then enters the leaves of the plants. Plants then removes Carbon Dioxide from the air, creating Oxygen. 
Photosynthesis
Sunlight
Sunlight
Carbon Dioxide
Water absorbed in roots
Photosynthesis is the process by which plants, bacteria and protistans use the energy from sunlight to produce glucose from carbon dioxide and water  
Oxygen exits
Oceans absorb Co2 from the atmosphere. Carbon is used to build the shells of marine organisms.
Humans burn fossil fuels. Sometimes, the Carbon in the atmosphere can become too much, so keeping the carbon cycle in balance is important to our