In the UK we had lots of art shows for kids while I was growing up including "Rolf's Cartoon Club" (I have long maintained that Rolf Harris should be the mascot for the creative commons movement) – but the undisputed king was Tony Hart, with shows such as "Take Hart" and "Hart Beat".
He, or his comely young art student assistants (one of which that I had a teenage crush on, I was to meet professionally in later life to my great amusement and embarrasment) would usually demonstrate a novel but accessible art technique which you could then impress your parents or teachers (never your peers) with at a later date.
I'm going to introduce one to you now, which I pioneered in San Franscisco earlier this month, while eating lunch at a conference/workshop.
I am a terrible doodler, and many a giant robot squirrel or rhino cocktail waiter has come to life from my pen during a meeting. This time a giant squid was born, and there happened to be a big roll of blue gaffer tape lying next to me, so I started assembling a mosaic/wash of blue behind the noble overlord of the deep.
Why not try it at home kids? Gaffer tape keeps on giving!