Of course, in the 6th form we were ever so senior, mature, and studious. Relatively speaking.
But we were schoolboys aged 12 or 13, and we still had some little diversions.
The desks at which we sat in class had lids that lifted to reveal an interior space for storing books, pens, rulers, etc. In the far right corner of the top of the desk was a round hole designed to hold an inkwell — although inkwells were already out of date in the 1960s. In the near left corner of the bottom of the desk was a slightly smaller round hole for convenience of cleaning: dust and debris could be swept into the corner and out through the hole.
It occurred to someone, somewhen, that a marble could be dropped into the first hole, and with suitable internal arrangements it could be made to drop out through the second hole. Thus was born the idea of the marble ramp.
A beginner's marble ramp, once he got it working correctly, would work rather fast: the marble would go rumble plonk, rumble plonk, rumble plonk, and drop out through the second hole. But this was rather boring and showed no finesse. A truly admirable marble ramp was distinguished by the length of time taken by the marble to emerge (the longer the better), and by the variety of interesting noises it made on the way.
One weekend we pooled our talents and materials, and set up an enormous marble ramp alongside two walls of the classroom — using piles of books, rulers, and other bits and pieces, as with a normal deskbound ramp. With a normal ramp, one marble at a time was used; but with this one, we dropped a whole bunch of marbles into it to see which would reach the end first. In places the marbles were visible as they raced; in other places they were hidden, and we could only hear the rumbling of them until they emerged into view again.
Having gone this far, we went further: we invited other boys in to bet on the marble races. A couple of us (don't look at me) knew about horse racing and were able to manage the betting in a professional manner. Of course it was all a bit silly because one marble is about as good as another; but it was a novelty and it seemed great sport.
Mr Angus got wind of the affair and was initially displeased; but he was persuaded to allow it to continue on condition that the proceeds went to charity. I suppose we had to dismantle the Great Ramp before lessons resumed on Monday.