Remember that these dabbed paintings are only 1.5″ x 2.5″.
Why not let your children paint the dabs on the wet paper and you can suggest an image from it. You could even paint the finished picture if they are too young. They would be amazed to see you produce a proper painting from their random splodges. Just remember not to have too much water with your colour for the dabs, as the paper is already wet and doesn’t need diluting further. Have fun!