Overheard: Simple Machines

Asher's first proposed Water Purification System, age 5

Asher: Dad, draw a tank.  Now draw a red button on top.  When the red button flashes, the water's dirty.  If the water's dirty, you gotta draw an oxygen pump.  There has to be a protein pump on the other side.  And on the top there has to be an energy pump.

Nate:  What's the source?  Where does the water come from?

Asher: From Africa dad.  Does Africa have dirty water?

Nate: Yeah, some of the water's dirty.

Asher: And America?

Nate: Yeah, Africa and America.

Asher: Ok, now draw waves,

This will clean the dirty water in Africa, but not just Africa.  Dirty water everywhere!"