I had two non-swimmer parents, my mum was always made afraid of the water by her mum who was also obviously a non swimmer and passed the fear on. We were never given an opportunity to go for swimming lessons, so I ended up teaching myself to swim, but as a result I am not a strong swimmer and don't like to go out of my depth. I was determined not to pass this on to my children, so they both started swimming lessons when they were about 3 years old, my eldest learnt to swim, though looking rather ungainly, but didn't really enjoy it so as soon I was satisfied that he could swim well enough to be able to give him a chance of getting to safety if he fell in anywhere, I let him stop his lessons. My daughter on the other hand is almost fearless in the water and has been from the start, she continued with her swimming lessons, right up to quite an advanced award, can't remember what though. So I consider it an important skill, along with a respect for the dangers of water without being made afraid of it. Again, I would have expected your g'kids to be more advanced than they are if they have been having lessons for such a long time. Might be worth having a word with the teacher or finding a different one.