Casting about for a new angle last week, I came upon the story of Larry Stuart, America's Secret Santa who, for the past 30 years or so, has been distributing $20 (pound;10) bills to the needy at Christmas time. He would walk the streets of New York each December and hand out the money to anyone he felt looked like they needed it, and over the years gave away around $670,000 (pound;340,182) in this manner.
His appearance on the streets was always anticipated, the more so as nobody knew the identity of this mystery benefactor. Last Christmas, shortly before his death, he revealed his identity because, he said, he wanted to highlight the impact of random acts of kindness.
Interestingly, he also explained the origins of his philanthropy. In the early 1970s, penniless and down on his luck, he had eaten a meal in a diner, knowing he would be unable to pay for it. As he prepared for his "lost my wallet" explanation, the owner of the diner spotted his plight.
Without fuss, he bent over and pretended to pick something up off the floor. Placing a $20 bill on the table, he said: "You must have dropped this."
Stuart never forgot this kindness and the preservation of his dignity and swore to replicate it if he ever had the means. He made his fortune in cable television and telecoms, and was thus able put his plan into action.
As a topic for assembly, of course, the story of how a few seconds of kindness can reverberate, as in the butterfly effect, through the years and among thousands of people, is perfect.
Naturally, I had to come up with a snappy ending, so my seniors received the wisdom: it seems that, whether with litter, in education, or in life, it is not what we drop that is important, but what we pick up.
Sean McPartlin is depute head of St Margaret's Academy, Livingston