We should make them well-aware, that they are the future generations, and they will suffer if there is lick of fuel. So, there must be some programs to spread awareness to them.
Then, include what is fuel and how to conserve it in the essay.
We must conserve the fuel, because it is depleting more and more. If we didn't conserve, then, will will suffer in the future, with no fuel, and so, no use of vehicles, etc... Also, more and m,ore use of fuels, leads to global warming.
Therefore, we are in a condition to conserve fuel, and we have to find the alternatives such as the CNG, battery vehicles, etc...
Without the help of children, this can't be done; because they are the future, even if we start to conserve, if they didn't know about the conservation of fuel, they, in their future, will waste the precious fuel.
So, the role of children is so important in making conservation of fuel, as a habit.

Thank you.
Hope this will help you.