Greta Youel loves going to swimming lessons. She greets the workers at the front desk, rolls off a big exercise ball into the deep end and shouts happily so she can hear how her voice echoes in the ...

Nine-year-old Isabella Caroll shoots off the pool’s edge, still full of energy after repeated laps in her level 3 swimming class. She’s fast, and her form is getting better. The shrieks and splashes ...