Are we able to undo the pollution?

We learnt about pollution through the online lessons.
The question asked to the children was; Are we able to undo the pollution?
This question for younger children was tough to answer as they needed to know what water pollution is?
I played the video about what is water pollution, and they understood what water pollution is?
They will prepare their own “river” then let to observe. Children were thrilled to see a clean and clear river.
Until I asked them to pour oil, they observed that their “river” became oily.
Then, I asked to throw the soil and trashes into their river.
At that moment, they knew what water pollution is.
For their last mission, I requested them to clean up their own “river” using any tools prepared by their parents.
I can see that every child was trying their best to clean up their “river”.
They found out that no matter how hard they tried, it is tough to undo the water pollution.
Finally, they concluded that it was “dirty” as they knew how hard they clean the polluted river.
It is still a dirty river as human beings polluted it.
Science lets them learn to save the environment and enables them to understand the consequences of polluting our rivers.
We teach the children a lesson which is ” Even the smallest act of caring for another person is like a drop of water. It will make ripples throughout the entire pond.”
Even a small action but we can change the world too.