| Just the other day I was in the parking lot of a Home Depot loading the kids into the minivan. I noticed in the bed of the truck parked next to me a load of yard trash (obviously on it's way to the dump). I reached in and grabbed a few cuttings of what looked like some common variety of croton. Clouds were rolling in and it started to rain...
As I put the cuttings in the trunk of our minivan my children started asking me why I was stealing from that truck (bless their hearts). I explained that the load was on it's way to the dump and we were going to try to save these cuttings.
As the storm rolled in that afternoon I set up a project area in the family room and layed out plactic tableclothes on the floor. We had potting soil, flats, water, rooting compound - the works. We spent the rest of that stormy afternoon preparing the cuttings... and making a huge mess. When we were finished I wrapped up the table clothe and threw it away. Just like that - all clean. Not only did we have fun but the kids learned a lot and have taken a personal interest in our garden.
Obviously depending on the age of your children you may want to control the use of rooting compound. | 
