Capezio Flex Mastr Tap Shoes - All Questions

says 2 1/2. I’m guessing that’s a capezio size.
We need at least full size bigger than what he is wearing. He wears a uk size 1 school shoe. Can you give any advice as to what size to order as I know capezio have their own sizes. Thank you Nichola.
https://www.dancedirect.com/cz443-capezio-tic-tap-toe-shoes