Add all ingredients to a high-powered blender and blend until smooth and creamy. If you are using Frozen Fruit, then it will be thicker. You can either add more milk or orange juice to adjust the consistency, or thaw the frozen fruit in a microwave to have a thinner consistency. Tip: I use my lemon press/squeezer to juice the oranges (they are just small enough to fit usually) instead of pulling out my juicer.
If you have picky kids, start with a small amount of greens and gradually increase as they get used to the taste.