- The kidneys receive blood from the renal artery - They process it with millions of tiny nephrons - Remove all the waste - The kidneys return the blood back to the body through the renal artery What might be the last step of the process?
Ans: Send the urine with the waste to the bladder through the ureters.

- A machine called a pulverizer grinds the coal into a fine powder - The coal powder mixes with hot air, which helps the coal burn more efficiently, and the mixture moves to the furnace - The burning coal heats water in a boiler, creating steam - Steam released from the boiler powers an engine called a turbine, transforming heat energy from burning coal into mechanical energy that spins the turbine engine - The spinning turbine is used to power a generator, a machine that turns mechanical energy into electric energy - This happens when magnets inside a copper coil in the generator spin - A condenser cools the steam moving through the turbine - As the steam is condensed, it turns back into water What might be the last step of the process?
Ans: The water returns to the boiler, and the cycle begins again

- Limestone is located under the soil - Rain picks up carbon dioxide as it falls to earth - The rain falls on the soil over the limestone - The carbon dioxide in the rain washes through the soil - The carbon dioxide turns into acid - The acid in the rain gets to the limestone below the soil - The acid dissolves the limestone - Acid continues to erode the limestone with more rain over time What might be the last step of the process?
Ans: The eroded limestone sometimes forms caves.

- The gravity of the sun pulls its mass inward - There is a lot of pressure on the Sun - The pressure forces atoms of hydrogen to fuse together in nuclear reactions - The energy from the reactions gives off different kinds of light What might be the last step of the process?
Ans: The light travels to the Earth.