When it comes to little girls and skirts, there is an 85% chance that their skirt isn't going to stay where it should. When climbing up slides and swinging on the monkey bars or doing somersaults in the yard, it's a guarantee that whatever is underneath will be making an appearance.
So, for those of us with little girls who beg for skirts and long to flip upside down, the answer is simple. It's a skort. There are a couple ways to go about making a skort. I was in the middle of creating a tutorial when I discovered one here. It is very similar to how I made mine so there is no point in rehashing all the details.
First you'll need to make a skirt. If you are starting out, I'd recommend a simple elastic waist skirt tutorial, but this will work with any skirt. Then you'll need to make a pair of shorts to go under. You can use a pattern or use a pair of existing shorts as a pattern. This pants tutorial will show you how.
The only changes in the skirt and shorts are that you don't have to account for an elastic casing so you'll actually use about an inch less fabric on top for both.
Perfect for blowing bubbles or doing cartwheels. Whatever.
You can use knit or a cotton woven fabric for the shorts.
I've used both but I prefer cotton knit for ease of wear.