NOTE: This project isn't for kids unless they're older. The cement mix is powdery and a hand irritant.
For the creative group, this project is fun and easy. Just wear gloves to be sure your hands don't get irritated. You can make several fun things with either straight cement or a mix of cement, sphagnum peat moss, or perlite; here are some Planters, bowls, garden balls. I like a bit of texture in my cement, so I add either Peat Moss or Perlite to the mix. You can experiment as you decide to make more things. The more things you find to make, the more creative you can be. You can add tints, texture, and even natural elements like grasses and seedpods. It's really important to use cement and not concrete. Quickcrete makes a great product that is available at almost every hardware and home-improvement store. For some of my planters, I used straight cement. The ones where I liked the air bubbles and a little bit of texture I mixed cement half and half with sphagnum peat moss. If you get really creative, you can add broken glass, plates, and other materials into the outside of your piece. 
For my mixing I purchased a large inexpensive plastic tub at the dollar store. Rather than using sticks to mix, since sometimes I like it thick and the stick doesn't hold up, rubber gloves work perfectly. Got those at the dollar store too. If you don't have plastic containers from food that you can upside go, the dollar store has a great selection often with varying sizes. When you're making a planter, you need a large container as your base, and an insert that is smaller to prevent cement from filling in the space where your plant will be. Sometimes I use paper as well. Milk containers are very interesting. You do have to find something for the center, because you don't want your concrete to be too thin. It all depends on what you're going to use. I don't have a picture, but I made a milk container planter/vase, and literally left the square glass vase that I got from a flower arrangement as the interior, so it is watertight. For globes, look for old light fixture globes, often under four dollars at thrift shops, garage sales, and even the Dollar store. It is handy to cut the interior of any of your "molds" with cooking spray. It allows the mold to slip away from the cement when it is dry. If you don't care about ruining your molds, you can cut away plastic, metal containers, and gently break any glass.
For any of your projects, you will mix the cement and your texture medium, add water so it's easy to work with (something like a peanut butter consistency is good) fill your container, and gently tap it to remove air bubbles. The runny or your mixture, the smoother your end result will be and the easier it will be to tapout the air bubbles. Once it has dried about 24 hours, sometimes even 48 when you use a lot of water, you can take your container off. In the case of the glass globe, it was safe wrapped in a hefty garbage bag, then tapped on my cement driveway to gently break the glass. The broken glass when into the recycling, in the bag can be shaken out and used again. Be sure to wear gloves so you do not get shards of glass in your hands.
