Have you tried painting with wet chalk? When my daughter was little she used to love dropping chalk into buckets of water. It actually used to drive me crazy, I would think, Oh no, she's ruining all the chalk. But in reality she was discovering a new way to work with an old material. Now we embrace wet chalk.
When I was an art teacher after doing a chalk project I used to be left with a box full of dirty mismatched chalk and never knew what to do with it. Well this is what you should do with it!
Easel (see homemade one below, masonite and duct tape)
Spray fixative (optional)
You can use any kind of chalk for this, it could be sidewalk chalk, or chalk pastels. If you are working with little kids I recommend sidewalk chalk, if you are working with elementary or high school kids use your old chalk pastels. Fill up a bowl with water and drop the oldest, dirtiest chalk pastels into the water.
I used black construction paper, but you could use any color of construction paper or white paper. You can even use wet chalk on wood, or sidewalks. When chalk is wet the colors appear brighter and smoother, kind of like paint.
I set this up in our backyard, using a lawn easel. What is a lawn easel you say? Well it's an easel that works best on the lawn and you can make it yourself. Go to Home Depot and pick out a sheet of masonite, then have them cut it into an even amount of pieces. The size depends on how big you want your easels to be. Masonite comes in different thickness, the thinner type will warp over time and the thick ones are quite heavy, so go for a medium thickness of masonite. Pick up some duct tape while you are there as well. Next connect two pieces of masonite at the top with duct tape and viola, you have an easel that can easily be folded up and stored under a bed or couch. Actually you will have more like 6 easels, so invite some friends over for an art play date!
Okay, back to the project. Set up your lawn easel and tape the paper down with blue painters tape. Set the bowl of wet chalk next to the easel and call your kids out to play.
Stand back and watch them create! If your kids are four or under just let them experiment with the material. If your kids are older you could suggest that they draw something in the backyard or you could even set up a still life for them.
The chalk will rub off, so if you would like to keep their drawings I recommend you spray them with a spray fixative. Do the spraying outside away from your kids because the spray is toxic to inhale. I usually pick their best one and spray it, the rest end up getting recycled. Your kids will want to do more than one of these, so be prepared with extra paper and tape.
Finally something to do with all those little pieces of old chalk! Have fun and let me know how it goes!