Pattern activities for kids in preschool through first grade - with links to free pattern printables -great Math resource!
Make pretend food for your kid's mud kitchen using stones. Such a brilliantly simple idea to combine with mud pies!
Reggio Inspired Numbers wall- photocopy kids hands and let them write the numbers
African Necklaces (made from Paper Plates)
Number formation display I think this is fabulous for engaging the boys. I would probably introduce one number at a time and slowly build it up.
Outdoor maths station
Doubling activity for Funky Fingers table
Pick a flower or plant and lay on top of a small piece of clay and use a rolling pin to make an imprint in the clay. let it harden. Paint. Add a magnet to the back.
Iceberg Experiment (glacier and iceberg flooding experiment under it too!)