What about focusing on the concept of organic shapes? For younger kids,
after showing appropriate Miro visual aids and discussing such, have the
students cut some interesting organic shapes from primary-colored
construction paper. We introduce the difference between organic and
geometric shapes in first grade, so you would either introduce or review
this concept here. Organic shapes have a tendency to look "like" something.
Have them glue these to a background (doing a rubbing with ocher crayon on
white paper using screen or some other surface to approximate the texture in
some of Miro's paintings might be fun - not too waxy, though). Using black
marker, make the shapes into animals, plants, people, etc., by adding lines.
For older kids, use the same technique to "interpret" another painting the
way Miro approximated the Dutch Baroque piece (was it a Jan Steen?) I hope
this helps. (Knowing this group, you'll get a zillion great ideas.)