One possibilty for showing movement based on Pollack is using marbles on
large paper. The students can roll them by holding the edges of the
paper and rolling the marble on the paper with different colored inks or
maybe thinned tempera paint. After they use round ones they can create
some unpredictable lines by sanding some sides of the marbles with sand
paper to create flat spots.
I dont know if this is what you are looking for...just an idea.