Christmas tree play dough circuits

We've previously played several times with 'electric' play dough using salt dough, a 9V battery and some LEDs to make a variety of circuits, including experimenting with series circuits and testing the conductivity of household objects.  It's been a few weeks since we did this, and I was trying to think of things to amuse the small boy whilst the rest of us were feeling under the weather at the weekend.  He's quite into all things Christmas themed at the moment so I decided to see if he could add some lights to a play dough Christmas tree.

I rolled out some play dough into a Christmas tree shape, with the positive side of the battery attached to one side of the tree, and the negative attached to the other.  There was a gap between the star at the top and one side of the tree, and again at the bottom between the tree trunk and the other side of the tree.  I then put various bits of play dough as tree decorations between the two sides, leaving gaps between everything.

The challenge for my son was then to find ways to put LEDs into the dough to light up the Christmas tree.  He managed to build a simple circuit with a yellow LED by the star, and then added some more LEDs across the middle (and found the star lit less brightly).  He added a few more LEDs between dough 'baubles' and then got bored and got the play dough scissors and cutters out...

One of the permutations of LEDs he created on the play dough tree

It turned into an interesting experiment of where he could cut the dough to break the circuit, and just how little dough needed to be connected for the electricity to flow.  He then removed all the baubles and decided to count them and do some sums with them (e.g. 4 red +  blue = 8) and then to put the LEDs in the home-made play dough his brother was playing with alongside him.  The little one loved the lights, and bizarrely made no attempt to eat them (which is why he had home-made dough, as he eats practically everything) although I was watching very closely!  Once he'd got 8 LEDs in parallel, he lost interest completely.

This wasn't entirely the activity I was hoping it might be when I set it up, but he seemed to enjoy it anyway.  It was a slightly different way of doing play dough circuits with the challenge of finding ways to connect LEDs between lumps of dough to make them light, and exploring what happened when additional LEDs were added in parallel.  You could just as easily set up a different shape which might appeal to your child instead.