Every time a child wants to or does derail a lesson it is mostly important to allow that derailing because it gives us information on how we are failing to teach not because we cannot but because we are standing there as teachers, with all the dumb accessories and phrases that teachers have.
Every time a child wants to or does derail a lesson it is important to ‘within reason’ allow that derailing because it reminds us that derailing a lesson is a natural or honest response to an unnatural or dishonest situation. All teaching should be a process of derailment. I am constantly surprised that more children are not constantly derailing more lessons.
If we insist on maintaining the difference and division between adults and children which does and does not exist, which should and should not exist, then we could at least watch, join in with or at least not put a stop to necessary derailments. The throwing of things, including paint, should be actively encouraged.
Also it is important to at least substitute the word share with the word divide. Share implies that someone owns and must unown in parts. Divide implies that a thing is and a way must be found to make it enough.
This does not apply to infinite things. Of them there is always enough or too much.