We spent last weekend building a board for Isaac's electric train set, and now we're practising running one train into the siding while the other loops around the main circuit. Isaac wants to run them both together and 'have a race'. Which engine will go faster? The bigger one, obviously. It's a battle between the Mallard (which any schoolchild knows was the fastest steam engine ever built) and a dumpy diesel-electric tank engine. No contest, then, in Isaac's view.
It reminds me of Piaget's Genevan studies on time, speed and distance. Claiming to have been put up to the challenge by Albert Einstein, with whom he had once shared an academic symposium, Piaget wanted to know whether children based their judgements of speed and distance on their reckoning about time, or whether their ideas about motion were more fundamental. Here's how I describe those experiments in the book:
Picking up on Einstein’s challenge, Piaget’s Genevan researchers presented children with various scenarios involving moving objects, such as clockwork snails crawling across a table, or two small dolls which were made to pass through tunnels of unequal length. Preoperational children would get hopelessly confused by questions about ‘how long’ and ‘how far’. Failing to take differences in speed, or starting and stopping points, into account, they might judge that something that had travelled further had also been travelling for more time. Slightly older children could use information about relative speed, such as the fact that one doll had overtaken another, but still tended to answer questions about temporal order in terms of spatial order: that is, interpreting questions about ‘before’ and ‘after’ in terms of distance rather than time.Our own experiment is not a particularly accurate reprise of those classic Genevan studies. The relative speeds of our two engines actually seem to be changing constantly: one minute the Mallard is outstripping the tank engine, and the next the smaller loco is making all the running. Isaac is excited; I'm plain emotional. Much of what we've arranged here comes from my old boyhood train set, some of which in turn dates back to a train set from the 1950s. Thirty years ago I packed a handful of tiny black track pins into a Freightliner container, thinking 'They'll be useful again one day.' Today I'm sifting them in my clumsy, grown-up fingers, and reflecting on the foresight of that long-ago ten-year-old.