Oil Pastels are different from crayons and chalk pastels. At Fibo, we use both chalk pastels and oil pastels.
Fibo recommends two brands for kids: Pentel and Expressions. Pentel pastels are good because they are thinner and offer a more precise ability to fill in smaller areas, whereas Expressions are good for filling in larger areas. However, if we had to choose having only one, we'd choose Pentel, because it gets super frustrating to use a big pastel when you need to fill in small things!
For pastels, we recommend buying a lot of colors, because it doesn't cost that much more but it's so much more fun!