Oh Mads, you need to come to our Gymbaroo. It is not in a big hall, they have separate rooms for mat time and equipment time - so it is HEATED in winter, and cooled in summer.
The sock thing is a standard Gymbaroo thing - so the children can develop better sensory perception through their feet. If the lawyers had anything to do with it, the children would be wearing steel capped boots for insurance reasons so they didn't stub their toes (no offence to lawyers intended!!)