My three-year-old son Joshua is a bright and curious boy, full of incessant questions and always wanting to get into everything.
The other day he noticed that when he was sucking up juice with a straw, the level of liquid in the cup went down. I pointed to the glass vase of tulips next to him and remarked that they also sucked up water to stay strong.
Joshua then wanted to know if he could see the level of water going down in the vase as well.
I told him that, unlike his juice straw, it happened too slowly for him to see it. But if he liked, we could do a little experiment to test whether it was happening.
Joshua knows what “spare-mints” are because he likes to watch “Nina and the Neurons” on CBeebies – a TV program in which a terrifyingly perky, white-coated host does interesting science with pre-school children.
Joshua was excited about the prospect, so we lined up an envelope on the vase, made a mark at the waterline, and wrote down the date and time next to the line. The envelope went on the fridge, and whenever Joshua wanted, we got it down and made a new mark corresponding to the new water level. As hoped, the tulips drank lots of water, with the level dropping about 3 mm every ten hours or so. We’re now on our second experiment with a new set of tulips, and he seems happy that it’s reproducible.
The staff at Joshua’s nursery has just asked me if I’d be willing to come in one morning to do a small science demonstration or experiment with the kids. This is a completely different brief, as it would have to be something that would have a real impact within half an hour, and which would be robust enough to withstand very short attention spans.
I’m stumped at the moment, so all ideas welcome!
I’ve had good fun making soap bubbes with school kids: you can talk about minimal area surfaces and get the to conjecture about what will happen if you stretch a soap film across an oddly-shaped wire frame. And if you have long enough hair you van make a pleasing demonstration about surface tension by
* taking a strand and tying the ends to form a circular loop
* wetting the loop with soappy water and then sliding it into an already-existing soap film (accross, say, a big wire ring)
* popping the bubble in the middle of the hair-loop.
Surface tension pulls the hair loop into a circle and you’re left with an annular soap film.
Put daffodils, carnations or any light coloured cut flower into a strong solution of food colouring. Very quickly, the flowers will begin to change colour and the children (and adults) will be able to see the ‘veins’ of the flower as the liquid travels up the stem and into the petals. Great fun, but the flowers don’t last very long as it is not their natural food source.
Grow amaryllis with the children. They grow at least 1cm a day and have a spectacular flower at the end.
Thanks for these ideas, folks!