Do you think Bruce would have to teach his kids how to swim?
Dick grew up in the circus, he probably had learned how to swim whenever it stopped somewhere, but he probably doesn't have much practice. and whenever Bruce tries to teach him more baby dick probably got sad because he remembers his parents teaching him to swim and how'd they let him hold on to their shoulder as he swam around. Maybe when he's closer to Bruce and it's time to get out of the pool, in an attempt to stop Bruce, he'll just grab onto him like a barnacle, and Bruce will just get out of the pool with him dangling from his shoulders. It reminds Bruce of what Thomas would do for him.
Bruce doesn't need to teach Babs how to swim; Gordon did. He remembers Gordon bringing a little Barbara to learn in his big pool. It was one of his first interactions with her, and whenever baby Dick would be a barnacle she would too, he'd carry both of them out of the pool giggling as the desperately tried to cling onto him. She and little Dick would race each other and have splash fights. Bruce had a pool lift installed for her so she had an easier time getting in the water.
He'd definitely have to teach Jason how to swim. I doubt there are many pools in crime alley, let alone teachers. The only body of water Jason would have really seen would have likely been Gotham Harbor, so trying to get him into the pool could have been him really excited to learn to swim, him refusing to leave the shallow end for ages and when he does he's clinging to Bruce the whole time, or he straight up refuses to get into a pool entirely. Jason had to relearn how to swim after he was dunked into the pit because he was so much bigger now and would sink much easier.
I wouldn't be surprised if the Drake had a pool, but there's no way they got an instructor for Tim. Tim probably would have had to get himself and an instructor and forge his parents' signature, or he would have learned by watching YouTube videos and almost drowning. Bruce might have only taught him what he needed for being Robin, or maybe Lady Shiva tied bricks to his ankles and tossed him into a pool so he could work on his lock picking, holding his breath, and swimming at the same time. Heck, maybe Bruce did this for Robin training.
Damian likely would have already known how to swim by the time he got to Bruce, but he was likely just thrown in the water and forced to figure it out. One of his fondest memories of the LOA could have been Talia holding him up in the pool as he learned how to float. This memory would always also remind him of how one of his instructors would dunk his head into the water for long periods to teach him to hold his breath.
Cass likely would have experienced a similar situation to Damian. David Cain probably just through her into the pool, and the only reason she didn't drown was because she was naturally buoyant. He likely taught her to hold her breath by holding her underwater; she would tear up his arm with her nails, but he'd only let her up when she stopped moving. She never actually learned to hold her breath; she learned to act like she was drowning sooner so he'd let her up. This made Bruce try to teach Cass to hold her breath underwater very hard.
Steph, like Jason, wouldn't have known how to swim, but Bruce doesn't teach her how to swim either, because he's focused on other things. She learns how to swim from YouTube videos and Bruce's occasional help. Swimming isn't her strong suit, and she always sits in a lounge chair whenever the other are in the pool, because she "hates swimming".
Duke would know very little about swimming, but he would know how to; his parents found one of the only community pools in Gotham so they could teach him. Growing up, they would go to the pool every once in a while and on Duke's birthdays. He loves swimming even if he wasn't that great at it until he had Bruce's training. Every year on his birthday, he still goes to that pool sometimes, but it closed sometimes after his parents were hospitalized.