Below are two examples of Hirst's spot paintings I printed out (he- and/or his assistants did more than 1500 of them). They range from tiny to huge. I showed the kids the painting with a woman standing next to it so they could understand the scale.
We had different approaches to the dots-project.
A symmetrical approach.
One that worked with the stickers in a three dimensional way.
A free style approach.
At the end of the session I gave the kids the surprise scratch paper.
And here some more photos of the warm up at the beginning of the session: drawing monsters and telling stories.