So What the Heck are Plimsolls?

The kids and I went to S’s new school to pick up uniforms and meet her teacher. Everyone is very nice and helpful. However, she needs to wear Plimsolls for gym. Huh? No trainers (tennis shoes). They showed me a plimsoll, so I could find them at a shoe store. They are little black shoes with a velcro strap. They are something between a tennis shoe and a dress shoe. I don’t know why you would wear them for gym, but…go with the flow.