Electric play dough

A friend who teaches science suggested this idea (thank you!) and I thought we had to try it. The basic idea is that salt dough conducts electricity so you can use it like wires to make circuits.

The small boy knows a little about electricity, although I'm not sure the extent to which his collection of facts (e.g. how a pantograph works, how it's generated by wind turbines, why things stop working when their batteries run out) add up to anything like a basic understanding.  I liked the idea of something that would let us talk about electricity and try to help him make a bit more sense of what he already knows.

I suggested that we might do "electric play dough" this morning, and he was very keen.  He got out his play dough (I've previously made our own, but at the moment we have ELC's Soft Stuff, which have lasted well) and I found some things he'd not seen before.  These were a 9V battery (PP3) and a clip for it with some wires on that I'd stripped back a bit and twisted round to give a bigger contact area, and 5 LEDs (red, blue, green, yellow and white).  We had a look at the battery, and I explained that we were going to make the electricity flow through the play dough to make the LEDs light up.  It turns out that he already knows that LEDs are lights thanks to Maddie Moate (apparently they are in police car lights...) and was excited to make lights in his play dough.

Simple play dough circuit with one red LED

We made a simple circuit with the battery, two bits of play dough and an LED bridging the gap between them.  I got him to try the LED both ways around to discover that it only lights up one way round.  I tried to explain that this is because it's something called a diode that only lets electricity flow one way, a bit like a one way street.  He liked this idea, and the fact that the LEDs have one longer 'leg' which helped us work out which way around it needed to be (long leg towards the positive terminal of the battery). 

Experimenting with play dough circuits

He tried out the different colours, and then we made some parallel circuits to get multiple LEDs to light at once - I explained this as like the electricity being able to choose lots of different roads to get back round its 'racetrack'.  He experimented with turning the LEDs around and was surprisingly careful putting them into the play dough (and it was nice and easy to get them to make good contacts). 

We had to stop because his brother lost patience with playing with toys on the floor (to avoid him eating either the dough or the LEDs!), but as I was asked to do my silly 'one way diode' voice several times this afternoon and evening, we'll no doubt be trying this one again soon...

NB. A word of caution if you try this - don't put the LEDs across the terminals of the battery, the play dough isn't a very good conductor so there's a lot of resistance in the circuits described above.


Comments

  1. After a bit of helpful feedback, I've had a go at a bit more explanation for electric play dough and what you can and can't do with it here: https://ossicones-and-oxygen.blogspot.com/2019/09/electric-play-dough-bit-more-explanation.html

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