I have seen the same concept using paint. But the great thing about oil pastels is you don't have to wait for them to dry. With Virginia the quicker the process the better. I actually tried this out by myself. I don't get to play with my art materials a lot. So I jumped at the chance when Virginia was busy watching Stampy and Breck was napping.
This project literally took 15 minutes start to finish. I cut out a simple square. I kept it small so it wouldn't take me long to finish. Then I colored the whole square with different colors. Next, the scary part I covered the whole design with a black oil pastel.
Once covered, I used a cuticle stick and a stencil to scratch out a design. This project was so fun and really addictive. It was fun seeing what colors popped up and just fun scratching off the black. Got project for kids to do by themselves. And you don't have to worry about being perfect, so all ages can do this craft.