Puzzles to puzzle you
. Lights out, please!
Turn all the lights out, if you can!  Changing a light also changes the lights next to it. So if the light was in the middle, changing it from on to off (or other way around) makes all the four lights surrounding it to also change. If the light was in a corner, the two next to it will also change. So you must choose to turn off or on lights so that all lights go off eventually. If you can solve this, try the slightly harder one to the right.
Answer: Start by pressing the light that is switched on in the centre of a batch of five. There are two such. You can solve the puzzle in two moves.